Water-jet guided laser processing lens and processing equipment

Abstract

The invention discloses a water-jet guided laser processing lens and processing equipment. The water-jet guided laser processing lens comprises a coupler, a lens shell and objective lens groups which are sequentially and coaxially arranged in the lens shell, and the objective lens groups comprise a negative lens group and a positive lens group. The negative lens group is used for diverging the laser beams to form divergent laser beams, the positive lens group is used for converging the divergent laser beams to form converged laser beams, and the coupler is used for coupling the converged laser beams from the positive lens group with high-pressure water jet to form water-guided laser beams. In the process that the laser beam sequentially passes through each lens in the objective lens group, a plurality of reflection focuses are formed, and each reflection focus is located outside the objective lens group. The invention aims to solve the problem that when a high-power laser beam is adopted as input in water-guided laser processing equipment, the laser beam can damage a lens in the equipment so as to maintain the normal processing operation of the equipment.

Description

Technical Field

[0001] The present application relates to the field of laser beam processing technology, and in particular to a water-guided laser processing lens and processing equipment. Background Art

[0002] Water jet guided laser technology (or water-guided laser technology) refers to the combination of high-energy pulsed laser and extremely fine high-pressure water jet (the water jet diameter is usually between 20-100 microns). The laser beam is coupled and fully confined in a stable, straight cylindrical water jet. The water jet acts as a waveguide for light, using the principle of total internal reflection to transmit laser energy from the laser head to the workpiece surface.

[0003] In some processing scenarios, high-power lasers are required to improve the efficiency of water-based laser processing equipment. Due to the high energy of high-power laser beams, they can damage the lenses used in water-based laser processing equipment. This damage is irreversible. In other words, damage to the lens caused by a high-energy laser beam is not reversed by the disappearance of the laser beam. Therefore, a lens damaged by the laser beam will become inoperable. Therefore, when water-based laser processing equipment uses high-power laser beams, how to design water-based laser processing lenses to prevent damage from the laser beam has become a pressing technical issue.

[0004] The above content is only used to assist in understanding the technical solution of this application and does not constitute an admission that the above content is prior art. Summary of the Invention

[0005] The main purpose of this application is to provide a water-guided laser processing lens and processing equipment, aiming to solve the problem that when a high-power laser beam is used as input in a water-guided laser processing equipment, the laser beam may damage the lens in the equipment, so as to maintain the normal processing operation of the equipment.

[0006] To achieve the above objectives, in a first aspect, the present application provides a water-guided laser processing lens, comprising: a coupler, a lens housing, and an objective lens group coaxially arranged in the lens housing, wherein the objective lens group may include: a negative lens group and a positive lens group.

[0007] The negative lens group is used to diverge the laser beam to form a diverging laser beam, while the positive lens group is used to converge the diverging laser beam to form a convergent laser beam. The coupler is used to couple the convergent laser beam from the positive lens group with a high-pressure water jet to form a water-guided laser beam. As the laser beam passes through each lens in the objective lens group, multiple reflection focal points are formed, each of which is located outside the objective lens group.

[0008] Among them, the lenses in the objective lens group are made of preset materials, and the thermal expansion coefficient of the preset materials is 0.5×10-7 / ℃~5.1×10 -7 / ℃.

[0009] Optionally, the preset material includes ultraviolet fused quartz glass or glass-ceramics.

[0010] Optionally, the negative lens assembly includes a negative meniscus lens. The first surface of the negative meniscus lens is concave, and the second surface is convex. The laser beam propagates to the negative meniscus lens, passes through the first surface and the second surface of the negative meniscus lens in sequence, and forms a first reflection focus, which is located outside the negative meniscus lens.

[0011] Optionally, the positive lens group includes: a plano-convex positive lens, a biconvex lens, a first positive meniscus lens and a second positive meniscus lens.

[0012] The first surface of the plano-convex positive lens is a plane, and the second surface of the plano-convex positive lens is a convex surface. The laser beam propagates to the plano-convex positive lens, passes through the first surface of the plano-convex positive lens and the second surface of the plano-convex positive lens in sequence, and forms a second reflection focus. The second reflection focus is located outside the negative lens group and the plano-convex positive lens.

[0013] The first and second surfaces of the biconvex lens are both convex surfaces. The laser beam propagates to the biconvex lens, passes through the first surface of the biconvex lens and the second surface of the biconvex lens in sequence, and forms a third reflection focus. The third reflection focus is located outside the negative lens group, the plano-convex positive lens and the biconvex lens.

[0014] The first surface of the first positive meniscus lens is convex, and the second surface is concave. The laser beam propagates to the first positive meniscus lens, passes through the first surface of the first positive meniscus lens and the second surface of the first positive meniscus lens in sequence, and forms a fourth reflection focus. The fourth reflection focus is located outside the negative lens group, the plano-convex positive lens, the biconvex lens and the first positive meniscus lens.

[0015] The first surface of the second positive meniscus lens is convex, and the second surface is concave. The laser beam propagates to the second positive meniscus lens, passes through the first surface of the second positive meniscus lens and the second surface of the second positive meniscus lens in sequence, and forms a fifth reflection focus. The fifth reflection focus is located outside the negative lens group, the plano-convex positive lens, the biconvex lens, the first positive meniscus lens and the second positive meniscus lens.

[0016] Optionally, among the negative meniscus lens, the plano-convex positive lens, the biconvex lens, the first positive meniscus lens and the second positive meniscus lens, the interval between two adjacent lenses is 0.3 mm to 0.7 mm.

[0017] The absolute value of the radius of curvature of the first surface of the negative meniscus lens is smaller than the absolute value of the radius of curvature of the second surface of the negative meniscus lens; the radius of curvature of the first surface of the biconvex lens is not equal to the radius of curvature of the second surface of the biconvex lens; the absolute value of the radius of curvature of the first surface of the first positive meniscus lens is smaller than the absolute value of the radius of curvature of the second surface of the first positive meniscus lens; the absolute value of the radius of curvature of the first surface of the second positive meniscus lens is smaller than the absolute value of the radius of curvature of the second surface of the second positive meniscus lens.

[0018] Optionally, the coupler includes a window and a nozzle; a cavity structure is formed between the window and the nozzle, the cavity structure including a water inlet; a high-pressure water jet enters the cavity structure through the water inlet, forming a water layer; and a surface of the nozzle connected to the cavity structure includes a water outlet. The laser beam sequentially passes through lenses in the objective lens assembly and propagates to the window. After passing through the window, it couples with the water layer to form a water-guided laser beam, which is then emitted through the water outlet.

[0019] Optionally, the interior of the nozzle includes a conical cavity structure, and the top of the conical cavity structure is connected to the cavity structure through the water outlet.

[0020] Optionally, the water-guided laser processing lens further includes: a first pressure ring, a second pressure ring, a third pressure ring, a first spacer ring and a second spacer ring; the interior of the lens housing is provided with an internal thread, a first boss, a second boss and a third boss.

[0021] The first pressing ring has an outer thread, and the outer thread of the first pressing ring cooperates with the thread inside the lens housing, so that the negative meniscus lens is fixed inside the lens housing. The first spacer is arranged between the negative meniscus lens and the plano-convex positive lens, and is used to fix the distance between the negative meniscus lens and the plano-convex positive lens. The second spacer is arranged between the biconvex lens and the plano-convex positive lens, and is used to fix the distance between the biconvex lens and the plano-convex positive lens, and so that the biconvex lens is pressed and fixed on the first boss. The second pressing ring has an outer thread, and the outer thread of the second pressing ring cooperates with the thread inside the lens housing, so that the first positive meniscus lens is fixed on the second boss. The third pressing ring has an outer thread, and the outer thread of the third pressing ring cooperates with the thread inside the lens housing, so that the second positive meniscus lens is fixed on the third boss.

[0022] In addition, to achieve the above-mentioned purpose, the present application also provides a water-guided laser processing device, including: the water-guided laser processing lens in the above-mentioned first aspect and any optional embodiment thereof, as well as a laser emitter and a camera module.

[0023] The laser transmitter is used to emit a laser beam. The water-guided laser processing lens is used to receive the laser beam and, based on the laser beam, form and emit a water-guided laser. The camera module is used to capture the laser beam reflected by the water-guided laser processing lens to generate a laser spot image.

[0024] Optionally, the water-guided laser processing equipment further includes a plano-convex collimator, a first reflector, and a second reflector, with the first reflector and the second reflector arranged parallel to each other. The plano-convex collimator is positioned near the laser emitter, with the optical axis of the plano-convex collimator passing through the center of the first reflector. A straight line connecting the center points of the first reflector and the second reflector is perpendicular to the optical axis of the plano-convex collimator. The laser beam emitted by the laser emitter forms a collimated laser beam after passing through the plano-convex collimator. The collimated laser beam is then reflected by the first and second reflectors in sequence and propagates to the water-guided laser processing lens.

[0025] Optionally, the water-guided laser processing apparatus further includes a third reflector disposed parallel to the first reflector and distal from the second reflector. The laser beam reflected by the water-guided laser processing lens propagates through the second reflector and the first reflector to the third reflector. The third reflector then reflects the laser beam to the camera module, allowing the camera module to form an image based on the captured laser beam.

[0026] The water-guided laser processing lens provided in the present embodiment utilizes a combination of positive and negative lens groups, ensuring that the multiple reflection focal points formed by the laser beam are located outside the objective lens group. This effectively prevents damage to the lens from the energy of the reflection focal points, ensuring stable operation. Furthermore, the lenses in the water-guided laser processing lens provided in the present embodiment are made of a material with a low thermal expansion coefficient, allowing them to operate in environments with high-power laser beams. Consequently, the water-guided laser processing lens provided in the present embodiment can be applied to water-guided laser processing equipment that utilizes high-pulse laser energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic structural diagram of a water-guided laser processing device provided in an embodiment of the present application; Figure 2 A schematic diagram of a water-guided laser processing lens provided in an embodiment of the present application; Figure 3 A light fan diagram of an optical system using preset optical data provided in an embodiment of the present application; Figure 4 A point diagram of an optical system using preset optical data provided in an embodiment of the present application; Figure 5 A modulation transfer function diagram of an optical system using preset optical data provided in an embodiment of the present application; Figure 6 A schematic diagram of wave aberration of an optical system using preset optical data provided in an embodiment of the present application; Figure 7Schematic diagram of the spherical aberration of each lens surface and the overall spherical aberration of the optical system using preset optical data provided in an embodiment of the present application; Figure 8 A schematic diagram of the reflection focus of each lens of an optical system using preset optical data provided in an embodiment of the present application.

[0028] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0031] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] The following is an explanation of the technical terms that appear in the examples of this application.

[0034] Abbe number: Also known as the "dispersion coefficient," it measures the degree of light dispersion in a transparent medium. Generally speaking, the greater the medium's refractive index, the greater the dispersion and the smaller the Abbe number; the smaller the medium's refractive index, the less dispersion and the larger the Abbe number.

[0035] Positive spherical aberration: The spherical surface has a stronger ability to converge (diverge) light far away from the optical axis than to converge to the near-axis light, resulting in the (virtual) convergence point of the light far away from the optical axis being in the positive direction of the (virtual) convergence point of the near-axis light, hence the name positive spherical aberration.

[0036] Negative spherical aberration: A spherical surface's ability to converge (diverge) light rays away from the optical axis is weaker than its ability to diverge near the axis. This causes the (virtual) convergence point of light rays away from the optical axis to lie in the negative direction of the (virtual) convergence point of the near-axis rays. This is called negative spherical aberration. Generally speaking, a lens that converges a light beam produces positive spherical aberration, while a lens that diverges a light beam produces negative spherical aberration.

[0037] It should be noted that the positive or negative spherical aberration is determined by the spherical surface and the relationship between the object and the image. A convex spherical surface can produce negative spherical aberration or positive spherical aberration, and the same is true for a concave spherical surface.

[0038] Spherical aberration correction: Optical design requires concave and convex spherical surfaces of different curvatures, that is, positive and negative lenses of different curvatures, to offset each other and minimize the spherical aberration of the entire system.

[0039] Numerical Aperture (NA): A dimensionless parameter in optical systems that quantifies the system's ability to collect light and its resolution. Specifically, NA directly reflects the angular range over which the system can collect light. A larger NA indicates greater light energy collection. For example, in a water-guided laser lens, a larger NA results in a smaller laser spot size for the same incident beam. This allows the laser beam to be coupled into a smaller nozzle, enabling the laser beam to be coupled with a smaller diameter high-pressure water jet, resulting in a smaller water jet diameter.

[0040] The operating principle of water-guided laser processing equipment is to couple a laser beam with a high-pressure water jet, confining the laser beam within the high-pressure water jet at a stable ratio. The water jet then propagates the laser beam to the workpiece surface. The laser processing lens in water-guided laser processing equipment includes multiple lenses that combine to converge the laser beam, allowing it to be better coupled to the high-pressure water jet.

[0041] In some implementations, the lens in the laser processing lens of the water-guided laser processing equipment is usually made of ordinary optical glass. However, in some processing scenarios, a high-power laser is required as the laser light source. If a high-power laser is directly used as the laser light source of the water-guided laser processing equipment, due to the high energy of the high-power laser light source and the large thermal expansion coefficient of ordinary optical glass (for example, the thermal expansion coefficient of ordinary optical glass K9 glass is 7.1×10 -6 / °C), this type of glass is prone to deformation with rising temperatures, which can damage the laser processing lens. Furthermore, prolonged exposure of a high-energy laser beam to the lens can cause thermal drift in the optical system due to the high temperature of the laser beam. Both lens damage and thermal drift can lead to failure of coupling between the laser beam and the water jet in water-guided laser processing equipment, potentially damaging the equipment.

[0042] Based on this, the present application provides a water-guided laser processing lens and processing equipment. The lens in the water-guided laser processing lens can be made of a lens with a thermal expansion coefficient of 0.5×10 -7 / ℃~5.1×10 -7 / °C material to prevent damage to the lens caused by the high-energy laser beam. Furthermore, this application also relies on a special lens combination and lens configuration, so that after the laser beam passes through each lens in sequence, it forms multiple reflected beam focal points (also referred to as reflection focal points, hereinafter collectively referred to as reflection focal points), each of which is located outside the lens. This can prevent excessive energy at the reflection focal point from causing thermal drift of the optical system, or excessive energy at the reflection focal point from damaging a lens.

[0043] The following first introduces the working principle of water-guided laser processing equipment in combination with its structure. Figure 1 , is a schematic diagram of the structure of a water-guided laser processing device provided in an embodiment of the present application. Figure 1 As shown, the processing equipment includes: a laser emitter 1, a water-guided laser processing lens 100 and a camera module, and the camera module includes: an imaging lens 20 and a camera 21.

[0044] Among them, a plurality of lenses can be arranged between the laser emitter 1 and the water-conducting laser processing lens 100, so that the laser beam emitted by the laser emitter 1 is transmitted to the water-conducting laser processing lens 100. Figure 1 As shown, the multiple lenses may include a plano-convex lens collimator 2 , a first reflector 3 and a second reflector 4 .

[0045] In one possible implementation, the image acquisition area of ​​the imaging lens 20 may also be provided with a third reflector 19, which is used to transmit the light reflected by the second reflector 4 to the imaging lens 20 so that the reflected light beam can be imaged in the imaging lens 20.

[0046] It should be understood that when the water-guided laser processing equipment is in operation, the laser emitter 1 emits a laser beam, which then sequentially passes through the plano-convex collimator 2, the first reflector 3, and the second reflector 4 to the water-guided laser processing lens 100. The water-guided laser processing lens 100 converges the laser beam, coupling the converged laser beam with a high-pressure water jet to form a water-guided laser beam, which then emits the water-guided laser. It should also be understood that the laser beam sequentially propagates through the lenses in the water-guided laser processing lens 100, generating a reflected laser beam. The reflected laser beam then propagates from the water-guided laser processing lens 100 to the second reflector 4, the first reflector 3, and the third reflector 19, and then, after being reflected by the third reflector 19, propagates to the imaging lens 20. Based on this, the camera 21 can capture a spot image of the laser beam through the imaging lens 20.

[0047] Please refer to Figure 2 , is a schematic diagram of a water-guided laser processing lens according to an embodiment of the present application. Figure 2 As shown, the water-guided laser processing lens 100 includes: a coupler 120, a lens housing 13, and an objective lens group coaxially arranged in the lens housing 13, wherein the objective lens group includes: a negative lens group and a positive lens group.

[0048] The negative lens group is used to diverge the laser beam to form a divergent laser beam, and the positive lens group is used to converge the divergent laser beam to form a convergent laser beam. The coupler 120 is used to couple the convergent laser beam from the positive lens group with a high-pressure water jet to form a water-guided laser beam. As the laser beam passes through each lens in the objective lens group in sequence, multiple reflection focuses can be formed, each of which is located outside the objective lens group. In addition, the lenses in the objective lens group are all made of a preset material, and the thermal expansion coefficient of the preset material can be 0.5×10 -7 / ℃~5.1×10 -7 / ℃.

[0049] like Figure 2As shown, the negative lens group may include a negative meniscus lens 5; the positive lens group may include a plano-convex positive lens 6, a biconvex lens 7, a first positive meniscus lens 8, and a second positive meniscus lens 9. The coupler 120 may include a window 10 and a nozzle 12. A cavity structure 11 may be formed between the window 10 and the nozzle 12. The cavity structure 11 may include a water inlet. The high-pressure water jet enters the cavity structure 11 through the water inlet to form a water layer. The top of the nozzle 12, i.e., the side of the nozzle 12 that contacts the cavity structure 11, may be provided with a water outlet so that the coupled water-guided laser beam is emitted through the water outlet.

[0050] For example, the interior of the nozzle 12 may include a conical cavity structure, and the conical cavity structure may be connected to the cavity structure 11 through a water outlet, so that the coupled water-guided laser beam may be emitted through the water outlet.

[0051] In some implementations, the negative lens group can also be a combination of a negative meniscus lens and a biconcave negative lens. It should be understood that the embodiments of the present application do not specifically limit the number and lens type of the negative lens group, as long as the purpose of the present application can be achieved in combination with the positive lens group.

[0052] In addition, each lens in the positive lens group has a converging effect on the laser beam. The positive lens group includes four lenses. It should be understood that in specific implementations, the positive lens group may also include fewer or more lenses. For example, the positive lens group may include a plano-convex positive lens, a first positive meniscus lens, and a second positive meniscus lens. It should be understood that the above is merely an example, and this embodiment does not limit the number of lenses in the positive lens group or the specific lens type, as long as it can achieve the objectives of this application in combination with the negative lens group.

[0053] It should be noted that when the laser beam propagates to the surface of each lens in the objective lens group, it will generate reflected light on the surface of the lens. In this case, if the reflection focus is located on the lens, since the energy of the reflected light is more concentrated at the focus, the energy of the reflection focus may cause damage to the lens. In order to avoid the occurrence of this problem, the design principle of each lens in this application is as follows: after the laser beam passes through each lens in the objective lens group in sequence, it forms multiple reflection focuses, and each reflection focus is not on the lens in the objective lens group. In addition, if Figure 2 As shown, multiple lenses in the objective lens group are combined together, and the lenses are cut from the plane where the optical axis of the objective lens group is located. From the cut surface, it can be observed that its external contour is similar to a "butterfly" shape.

[0054] In order to better adapt to working in high-power laser scenarios, the lens in the water-guided laser processing lens 100 can be made of a material with a low thermal expansion coefficient. For example, ultraviolet fused silica glass or microcrystalline glass can be used. The thermal expansion coefficient of ultraviolet fused silica glass is 5.1×10 -7 / ℃, the softening point is 1585℃, and the thermal stability is high. The thermal expansion coefficient of microcrystalline glass is 0.5×10 -7 It should be understood that the above materials are only examples, and in actual applications, other materials with lower thermal expansion coefficients can also be used, and this application does not limit this.

[0055] In one possible embodiment, the first surface of the negative meniscus lens is concave and the second surface is convex. It should be understood that the negative meniscus lens has a diverging effect on the laser beam and produces negative spherical aberration on the laser beam. Optionally, the radius of curvature of the first surface of the negative meniscus lens can be -30 mm to -20 mm, the radius of curvature of the second surface can be -73 mm to -68 mm, the refractive index can be 1.3 to 1.5, and the Abbe number can be 66.8 to 68.2. Exemplarily, the radius of curvature of the first surface of the negative meniscus lens can be -26.63 mm, the radius of curvature of the second surface can be -71.63 mm, the refractive index Nd of the negative meniscus lens can be 1.458, the Abbe number Vd can be 67.821, and the center thickness can be 4 mm.

[0056] In one possible embodiment, the first surface of the plano-convex positive lens is a plane, and the second surface is a convex surface. It should be understood that the plano-convex positive lens has a converging effect on the laser beam and produces positive spherical aberration in the laser beam. Optionally, the radius of curvature of the second surface of the plano-convex positive lens can be -56.00 mm to -53.00 mm, the refractive index can be 1.3 to 1.5, and the Abbe number can be 66.8 to 68.2. Exemplarily, the radius of curvature of the second surface of the plano-convex positive lens can be -55.59 mm, the refractive index Nd of the plano-convex positive lens can be 1.458, the Abbe number Vd can be 67.821, and the center thickness can be 6 mm.

[0057] In one possible embodiment, the first and second surfaces of the biconvex lens are both convex surfaces, and the curvatures of the two surfaces are different. It should be understood that the biconvex lens has a converging effect on the laser beam and produces positive spherical aberration on the laser beam. Optionally, the radius of curvature of the first surface of the biconvex lens can be 50.00mm~54.00mm, the radius of curvature of the second surface of the biconvex lens can be -148.00mm~-145.00mm, the refractive index can be 1.3~1.5, and the Abbe number can be 66.8~68.2. Exemplarily, the radius of curvature of the first surface of the biconvex lens can be 51.22mm, the radius of curvature of the second surface can be -146.17mm, the refractive index Nd of the biconvex lens can be 1.458, the Abbe number Vd can be 67.821, and the center thickness can be 7mm.

[0058] In one possible embodiment, the first surface of the first positive meniscus lens is convex and the second surface is concave. It should be understood that the first positive meniscus lens has a converging effect on the laser beam and produces positive spherical aberration on the laser beam. Optionally, the radius of curvature of the first surface of the first positive meniscus lens can be 20.00mm~25.00mm, the radius of curvature of the second surface of the first positive meniscus lens can be 80.00mm~89.00mm, the refractive index can be 1.3~1.5, and the Abbe number can be 66.8~68.2. Exemplarily, the radius of curvature of the first surface of the first positive meniscus lens can be 23.13mm, the radius of curvature of the second surface can be 86.9mm, the refractive index Nd of the first positive meniscus lens can be 1.458, the Abbe number Vd can be 67.821, and the center thickness can be 7mm.

[0059] In one possible embodiment, the first surface of the second positive meniscus lens is convex and the second surface is concave. It should be understood that the second positive meniscus lens has a converging effect on the laser beam and produces positive spherical aberration on the laser beam. Optionally, the radius of curvature of the first surface of the second positive meniscus lens can be 10.00mm~15.00mm, the radius of curvature of the second surface of the second positive meniscus lens can be 19.00mm~24.00mm, the refractive index can be 1.3~1.5, and the Abbe number can be 66.8~68.2. Exemplarily, the radius of curvature of the first surface of the second positive meniscus lens can be 13.88mm, the radius of curvature of the second surface can be 21.72mm, the refractive index Nd of the second positive meniscus lens can be 1.458, the Abbe number Vd can be 67.821, and the center thickness can be 8mm.

[0060] In a possible implementation, among the negative meniscus lens, the plano-convex positive lens, the biconvex lens, the first positive meniscus lens, and the second positive meniscus lens, the spacing between two adjacent lenses may be 0.3 mm to 0.7 mm.

[0061] For example, the spacing distance between the second surface of the negative meniscus lens and the first surface of the plano-convex positive lens can be 0.5 mm, the spacing distance between the second surface of the plano-convex positive lens and the first surface of the biconvex lens can be 0.5 mm, the spacing distance between the second surface of the biconvex lens and the first surface of the first positive meniscus lens can be 0.5 mm, and the spacing distance between the second surface of the first positive meniscus lens and the second surface of the second positive meniscus lens can be 0.5 mm. For example, the spacing distance between adjacent lenses can also be set to other values ​​such as 0.4 mm, 0.6 mm, or 0.7 mm, and the spacing distances between different lenses can be equal or unequal, which is not limited in this application.

[0062] It is understandable that the above parameter settings are only examples, and the specific values ​​can be adjusted based on actual conditions, and this application does not limit this.

[0063] In one possible embodiment, the lens housing 13 may have threads and a frustum inside for mounting multiple lenses in the objective lens group; the lens housing 13 may be a cylinder made of metal, and multiple lenses may be fixed inside the lens housing 13 by threads and pressure rings or spacers.

[0064] For example, please refer to Figure 2 ,like Figure 2 As shown, in a possible embodiment, the water-guided laser processing lens 100 may further include: a first pressure ring 18, a second pressure ring 15, a third pressure ring 14, a first spacer ring 17 and a second spacer ring 16, and a first boss, a second boss and a third boss may also be provided inside the lens housing 13.

[0065] The first pressing ring 18 may have an outer thread, and the outer thread of the first pressing ring 18 can cooperate with the thread inside the lens housing 13 to fix the negative meniscus lens 5 inside the lens housing 13. The first spacer ring 17 can be disposed between the negative meniscus lens 5 and the plano-convex positive lens 6 to fix or adjust the distance between the negative meniscus lens 5 and the plano-convex positive lens 6. The second spacer ring 16 can be disposed between the biconvex lens 7 and the plano-convex positive lens 6 to fix or adjust the distance between the biconvex lens 7 and the plano-convex positive lens 6, and can press and fix the biconvex lens 7 on the first boss. The second pressing ring 15 may have an outer thread, and the outer thread of the second pressing ring 15 can cooperate with the thread inside the lens housing 13 to fix the first positive meniscus lens 8 on the second boss. The third pressing ring 14 has an outer thread, and the outer thread of the third pressing ring 14 cooperates with the thread inside the lens housing 13 (i.e., a threaded connection) to fix the second positive meniscus lens 9 on the third boss. It should be understood that in the process of installing multiple lenses in sequence, while ensuring the spacing distance between each lens, it is also necessary to ensure that the optical axes of these lenses coincide with a straight line, that is, the optical axes of the negative meniscus lens 5, the plano-convex positive lens 6, the biconvex lens 7, the first positive meniscus lens 8 and the second positive meniscus lens 9 are coaxial.

[0066] In one possible implementation, Figure 1 As an example, the water-guided laser processing equipment shown in the figure is used. Figure 2 When the objective lens group of the structure shown is used as the lens of the water-guided laser processing equipment, the specific setting data of the lens or mirror used can be shown in Table 1.

[0067] Table 1: Optical lens data sheet

[0068] In one possible implementation, the upper surface of the first reflector 3 can be coated with a highly reflective film, while the lower surface of the first reflector 3 can be uncoated. It should be understood that the reflectivity of the upper surface coated with the highly reflective film can reach 99.9%. Based on this, when the laser beam propagates to the upper surface of the first reflector 3, it can be reflected by the upper surface, changing the propagation direction of the laser beam. In another possible implementation, the lower surface of the second reflector 4 can be coated with a highly reflective film. When the laser beam is reflected by the first reflector 3 and propagates to the second reflector 4, it can be reflected by the lower surface of the second reflector 4, changing the propagation direction of the laser beam.

[0069] In one possible implementation, the second reflector 4 can be parallel to the first reflector 3. It should be understood that when the angle of the second reflector 4 is adjusted, the propagation direction of the laser beam reflected by the second reflector 4 will also be deflected. Therefore, before use, the angle of the second reflector 4 can be adjusted so that the focal position of the laser beam reflected by the second reflector 4 is at the same position as the center of the circular hole on the upper surface of the nozzle 12.

[0070] It should be noted that for conventional water-guided laser processing equipment, when the laser beam emitted by the laser passes through a 150um or 200um fiber core, the diameter of the nozzle 12 in the coupler 120 is typically 80um, 60um, or 50um. However, with the processing equipment provided herein, the diameter of the laser beam's focused spot can be reduced to 20um for the same incident laser beam. Therefore, the laser beam can be coupled into the smaller-diameter nozzle 12, reducing the diameter of the water-guided laser beam to 40um. Compared to a conventional water-guided laser beam with an 80um diameter emitted by a nozzle 12, this effectively reduces the processing gap width of the water-guided laser beam. Furthermore, when the processing equipment provided herein is used for surface processing of precious materials, material loss can be effectively reduced. Furthermore, with the water-guided laser processing lens provided herein, the smaller diameter of the nozzle 12 also results in a smaller diameter of the water-guided laser beam, resulting in a higher energy density within the water-guided laser beam, effectively shortening processing time.

[0071] Please refer to Figure 3 , is the optical system light fan diagram of the water-guided laser processing equipment using the optical data in Table 1 above. Figure 3 As shown in the figure, the ray fan diagram reflects the lateral aberration of the optical system. It can be seen from the figure that the global lateral aberration is less than 1 μm. This shows that the optical system determined by the above optical data can well concentrate the power of the laser beam and reduce the possibility of distortion.

[0072] Please refer to Figure 4 , is the optical system point diagram of the water-guided laser processing equipment using the optical data in Table 1 above. Figure 4As shown in the figure, the root mean square (RMS) radius of the diffuse spot is 0.476 μm, which is smaller than the 0.522 μm radius of the Airy disk. This means that the optical system using this data forms a very small spot, indicating that the laser beam propagates through the water layer and can couple well with the water jet to form a water-guided laser beam.

[0073] Please refer to Figure 5 , is a modulation transfer function diagram of the optical system of the water-guided laser processing equipment using the optical data in Table 1 above. Figure 5 As shown in the figure, the horizontal axis represents spatial frequency, and the vertical axis represents the optical transfer function (OTF) modulus. At a spatial frequency of 2.4e3, the OTF modulus is essentially aligned with the diffraction limit, approaching ideal imaging. The optical transfer function (OTF) is a function that uses spatial frequency as a variable to characterize the relative changes in modulation and lateral phase shift during the imaging process.

[0074] Please refer to Figure 6 , is a schematic diagram of the wave aberration of the optical system of the water-guided laser processing equipment using the optical data in Table 1 above. Figure 6 As shown, the optical path difference of the optical system is between +0.03 and -0.01 wavelengths, which is extremely small.

[0075] Please refer to Figure 7 , is a schematic diagram of the spherical aberration of each surface of the optical system lens and the overall spherical aberration of the system of the water-guided laser processing equipment using the optical data in Table 1 above. Among them, 2-1 represents the first surface of the plano-convex lens collimator, and 2-2 represents the second surface of the plano-convex lens collimator; 5-1 represents the first surface of the negative meniscus lens, and 5-2 represents the second surface of the negative meniscus lens; 6-1 represents the first surface of the plano-convex positive lens, and 6-2 represents the second surface of the plano-convex positive lens; 7-1 represents the first surface of the biconvex lens, and 7-2 represents the second surface of the biconvex lens; 8-1 represents the first surface of the first positive meniscus lens, and 8-2 represents the second surface of the first positive meniscus lens, 9-1 represents the first surface of the second positive meniscus lens, and 9-2 represents the second surface of the second positive meniscus lens. Since the light beam needs to converge to the window for incidence, and the window is a parallel flat glass, negative spherical aberration will inevitably occur. These spherical aberrations need to be offset by the spherical surface of the objective lens group, such as Figure 7As shown, the negative spherical aberration generated by the first surface 5-1 of the negative meniscus lens is -0.395073mm, the positive spherical aberration generated by the first surface 6-1 of the plano-convex positive lens is 0.0158mm, and the positive spherical aberration generated by the second surface 6-2 of the plano-convex positive lens is 0.090009mm; the positive spherical aberration generated by the first surface 7-1 of the biconvex lens is 0.135585mm, and the positive spherical aberration generated by the second surface 7-2 of the biconvex lens is 0.1865mm; the first positive meniscus lens The first surface 8-1 produces a positive spherical aberration of 0.029mm, while the second surface of the first positive meniscus lens produces a positive spherical aberration of 0.168401mm. The first surface 9-1 of the second positive meniscus lens produces a negative spherical aberration of -0.085577mm, while the second surface 9-2 of the second positive meniscus lens produces a positive spherical aberration of 0.17633mm. The negative spherical aberration produced by the window is -0.328422mm, while the positive spherical aberration produced by the water layer is 0.003527mm. The total spherical aberration produced by the entire optical system is a positive spherical aberration of 0.006205mm. Therefore, by matching the spherical aberration of each surface, this optical system achieves the required overall spherical aberration while minimizing aberrations.

[0076] Please refer to Figure 8 , is a schematic diagram of the reflection focus of each lens of the optical system using the optical data in Table 1 above. Figure 8 As shown, 81 is a schematic diagram of the reflection focus formed when the laser beam propagates to the second surface 2-2 of the plano-convex lens collimator; 82 is a schematic diagram of the reflection focus formed when the laser beam propagates to the first surface 5-1 of the negative meniscus lens; 83 is a schematic diagram of the reflection focus formed when the laser beam propagates to the second surface 5-2 of the negative meniscus lens; 84 is a schematic diagram of the reflection focus formed when the laser beam propagates to the first surface 6-1 of the plano-convex positive lens; 85 is a schematic diagram of the reflection focus formed when the laser beam propagates to the second surface 6-2 of the plano-convex positive lens; 86 is a schematic diagram of the reflection focus formed when the laser beam propagates to the first surface 7-1 of the double convex lens; 87 is a schematic diagram of the laser beam Figure 88 is a schematic diagram of the reflection focus formed when the laser beam propagates to the second surface 7-2 of the biconvex lens; Figure 89 is a schematic diagram of the reflection focus formed when the laser beam propagates to the second surface 8-2 of the first positive meniscus lens; Figure 90 is a schematic diagram of the reflection focus formed when the laser beam propagates to the first surface 9-1 of the second positive meniscus lens; Figure 91 is a schematic diagram of the reflection focus formed when the laser beam propagates to the second surface 9-2 of the second positive meniscus lens; Figure 92 is a schematic diagram of the reflection focus formed when the laser beam propagates to the window; Figure 93 is a schematic diagram of the reflection focus formed when the laser beam propagates to the nozzle. It can be seen that the reflection focus of the lens surface in the water-guided laser processing lens using the above optical data is not on the objective lens group.

[0077] The above example demonstrates that lenses made of UV fused quartz have a low thermal expansion coefficient and a high softening point, improving the optical stability of water-guided laser lenses. Looking at the overall structure of the objective lens assembly, if the objective lens assembly is cut along its optical axis, the cut surface reveals that the lens assembly forms a "butterfly" shape with a thin center and thick edges. This controls the laser's reflection focus outside the lens assembly, preventing damage to the lens from excessive reflected energy.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A water-guided laser processing lens, characterized in that: include: A coupler, a lens housing, and an objective lens group coaxially arranged in the lens housing, wherein the objective lens group includes a positive lens group and a negative lens group; The negative lens group is used to diverge the laser beam to form a divergent laser beam, the positive lens group is used to converge the divergent laser beam to form a convergent laser beam, and the coupler is used to couple the convergent laser beam from the positive lens group with a high-pressure water jet to form a water-guided laser beam; In the process of the laser beam passing through each lens in the objective lens group in sequence, a plurality of reflection focuses are formed, and each reflection focus is located outside the objective lens group; The lenses in the objective lens group are all made of a preset material, and the thermal expansion coefficient of the preset material is 0.5×10 -7 / ℃~5.1×10 -7 / ℃.

2. The water-guided laser processing lens according to claim 1, characterized in that: The preset material includes: ultraviolet fused quartz glass or microcrystalline glass.

3. The water-guided laser processing lens according to claim 1, characterized in that: The negative lens group includes a negative meniscus lens; The first surface of the negative meniscus lens is concave, and the second surface is convex; the laser beam propagates to the negative meniscus lens, passes through the first surface of the negative meniscus lens and the second surface of the negative meniscus lens in sequence, and forms a first reflection focus, which is located outside the negative meniscus lens.

4. The water-guided laser processing lens according to claim 3, characterized in that: The positive lens group includes: a plano-convex positive lens, a biconvex lens, a first positive meniscus lens and a second positive meniscus lens; The first surface of the plano-convex positive lens is a plane, and the second surface of the plano-convex positive lens is a convex surface. The laser beam propagates to the plano-convex positive lens, passes through the first surface of the plano-convex positive lens and the second surface of the plano-convex positive lens in sequence, and forms a second reflection focus. The second reflection focus is located outside the negative lens group and the plano-convex positive lens. The first surface and the second surface of the biconvex lens are both convex surfaces, the laser beam propagates to the biconvex lens, passes through the first surface and the second surface of the biconvex lens in sequence, and forms a third reflection focus, and the third reflection focus is located outside the negative lens group, the plano-convex positive lens, and the biconvex lens; The first surface of the first positive meniscus lens is convex, and the second surface is concave. The laser beam propagates to the first positive meniscus lens and passes through the first surface of the first positive meniscus lens and the second surface of the first positive meniscus lens in sequence to form a fourth reflection focus. The fourth reflection focus is located outside the negative lens group, the plano-convex positive lens, the biconvex lens, and the first positive meniscus lens. The first surface of the second positive meniscus lens is convex, and the second surface is concave. The laser beam propagates to the second positive meniscus lens, passes through the first surface of the second positive meniscus lens and the second surface of the second positive meniscus lens in sequence, and forms a fifth reflection focus. The fifth reflection focus is located outside the negative lens group, the plano-convex positive lens, the biconvex lens, the first positive meniscus lens, and the second positive meniscus lens.

5. The water-guided laser processing lens according to claim 4, characterized in that: Among the negative meniscus lens, the plano-convex positive lens, the biconvex lens, the first positive meniscus lens, and the second positive meniscus lens, the interval between two adjacent lenses is 0.3 mm to 0.7 mm; The absolute value of the radius of curvature of the first surface of the negative meniscus lens is smaller than the absolute value of the radius of curvature of the second surface of the negative meniscus lens; the radius of curvature of the first surface of the biconvex lens is not equal to the radius of curvature of the second surface of the biconvex lens; The absolute value of the radius of curvature of the first surface of the first positive meniscus lens is smaller than the absolute value of the radius of curvature of the second surface of the first positive meniscus lens; the absolute value of the radius of curvature of the first surface of the second positive meniscus lens is smaller than the absolute value of the radius of curvature of the second surface of the second positive meniscus lens.

6. The water-guided laser processing lens according to any one of claims 1 to 5, characterized in that: The coupler includes a window and a nozzle; a cavity structure is formed between the window and the nozzle, and the cavity structure includes a water inlet; the high-pressure water jet enters the cavity structure through the water inlet to form a water layer, and the side of the nozzle connected to the cavity structure includes a water outlet; The laser beam sequentially passes through the lenses in the objective lens group and propagates to the window. After passing through the window, the laser beam couples with the water layer to form a water-guided laser beam. The water-guided laser beam is emitted through the water outlet.

7. The water-guided laser processing lens according to claim 6, characterized in that: The interior of the nozzle includes a conical cavity structure, and the top of the conical cavity structure is connected to the cavity structure through the water outlet.

8. The water-guided laser processing lens according to claim 4 or 5, characterized in that: The water-guided laser processing lens further comprises: a first pressing ring, a second pressing ring, a third pressing ring, a first spacer ring and a second spacer ring; the interior of the lens housing is provided with an internal thread, a first boss, a second boss and a third boss; The first pressing ring has an outer thread, and the outer thread of the first pressing ring cooperates with the inner thread of the lens housing so that the negative meniscus lens is fixed inside the lens housing; The first spacer is provided between the negative meniscus lens and the plano-convex positive lens, and is used to fix the distance between the negative meniscus lens and the plano-convex positive lens; The second spacer is provided between the biconvex lens and the plano-convex positive lens, and is used to fix the distance between the biconvex lens and the plano-convex positive lens, and to enable the biconvex lens to be pressed and fixed on the first boss; The second pressing ring has an outer thread, and the outer thread of the second pressing ring cooperates with the inner thread of the lens housing, so that the first positive meniscus lens is fixed on the second boss; The third pressing ring has an outer thread, and the outer thread of the third pressing ring cooperates with the thread inside the lens housing, so that the second positive meniscus lens is fixed on the third boss.

9. A water-guided laser processing device, characterized in that: include: The water-guided laser processing lens according to any one of claims 1 to 8; As well as, laser transmitter and camera module; The laser emitter is used to emit a laser beam; The water-guided laser processing lens is used to receive the laser beam and form and emit a water-guided laser based on the laser beam; The camera module is used to obtain the laser beam reflected by the water-guided laser processing lens to generate a laser spot image.

10. The water-guided laser processing equipment according to claim 9, characterized in that: The water-guided laser processing equipment further includes a plano-convex lens collimator, a first reflector and a second reflector, wherein the first reflector is arranged in parallel with the second reflector; The plano-convex lens collimator is arranged near the laser emitter, and the optical axis of the plano-convex lens collimator passes through the center of the first reflector; A straight line is formed by connecting the center point of the first reflector and the center point of the second reflector, wherein the straight line is perpendicular to the straight line where the optical axis of the plano-convex lens collimator is located; The laser beam emitted by the laser emitter forms a collimated laser beam after passing through the plano-convex lens collimator. The collimated laser beam is reflected by the first reflector and the second reflector in sequence and propagates to the water-guided laser processing lens.

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