Water guide laser water light coupling multi-focal point spherical lens system and optimization method

Abstract

The present application belongs to the technical field of laser water jet composite machining, and relates to a water guide laser water light coupling multi-focal point spherical lens system and an optimization method, comprising a multi-focal point spherical lens, a laser source system, a coupling cavity, a high-pressure water pump and a machining nozzle; the focusing surface of the multi-focal point spherical lens is composed of multiple coaxial spherical surface segments with different radii of curvature, and the centers of the spherical surface segments are located on the optical axis of the lens; after the laser beam is refracted by the composite surface, a plurality of axially spaced focusing point arrays are formed along the optical axis inside the light guide water jet, the total laser energy is dispersed to the multiple focal points, and the energy density of a single focal point is reduced; the present application forms multiple focusing points arranged in order along the water column axis by the lens, reduces the energy density of a single focal point by 30% to 60%, and lowers the peak energy below the critical threshold of water column gas explosion, thereby completely eliminating the faults such as bubble generation, water column fracture and light path scattering loss caused by water molecule vaporization under the action of high-power laser.

Description

Technical Field

[0001] This invention belongs to the field of laser-water jet composite processing technology, specifically relating to a water-guided laser-water-optical coupled multi-focus spherical lens system and its optimization method. Background Technology

[0002] In the field of precision manufacturing, water-guided laser processing combines the advantages of high-precision laser cutting with water jet cooling and chip removal. It is a mainstream processing method for hard and brittle materials such as sapphire, silicon carbide, and quartz glass, as well as high-hardness alloys and composite materials, and is widely used in high-end manufacturing scenarios such as semiconductor chip packaging, aerospace components, and medical devices. It relies on a 0.1–0.5 mm high-pressure micro-water column as the light guiding medium. The laser is focused by a lens and coupled into the water column. Low-loss energy transmission is achieved through total internal reflection at the water-light interface, and the material is melted and vaporized through a high-energy laser spot.

[0003] The power limit and processing stability of existing water-guided laser systems are severely limited by the traditional focusing lens structure. Conventional focusing lenses employ a single spherical or aspherical continuous curved surface structure, which can only form a single concentrated focal point inside the water column. This structure can be used normally under low-power conditions of 50W and below, but when the laser power exceeds 50W, the single-point energy density will exceed 102. 8 The W / cm² water column explosion threshold; water molecules within the water column rapidly vaporize under the impact of high-energy laser, generating numerous microbubbles that disrupt the total internal reflection optical path, resulting in 30%–50% laser energy loss. The periodic generation and collapse of these bubbles generate impact loads, which can degrade the workpiece surface roughness from 0.1μm to over 0.5μm, and in severe cases, directly break the water column, causing processing interruption; simultaneously, the high heat at a single point exacerbates lens heat loss, shortens the lifespan of optical components, and significantly reduces the stability of continuous processing.

[0004] Existing improvement methods in the industry all have significant shortcomings and cannot fundamentally solve the problem of concentrated energy at a single point: First, reducing the duty cycle of the laser pulse and splitting the output into sub-pulses with time-division output can alleviate gas explosions, but the processing efficiency is greatly reduced, making it difficult to meet mass production requirements and increasing the cost of circuit control hardware; Second, increasing the water column pressure and optimizing the nozzle structure can only increase the critical withstand power by 10% to 15%, with a weak improvement effect, and the equipment energy consumption and maintenance costs increase significantly; Third, using ordinary aspherical or gradient refractive index lenses only slightly extends the focal length and cannot disperse the peak energy at a single point, so the problem of water column gas explosion still exists under high power.

[0005] As semiconductor processes iterate towards 3nm and the aerospace industry widely adopts lightweight, high-hardness, and difficult-to-process materials, the industry's demand for high-power, high-efficiency, and high-precision water-guided laser processing continues to increase. However, traditional single-focusing lenses have become a core bottleneck restricting equipment power upgrades and processing performance improvements. Therefore, there is an urgent need for a novel water-optical coupling focusing lens structure to disperse laser energy at the optical structure level and eliminate water column gas explosion defects under high-power conditions. Summary of the Invention

[0006] This invention provides the following technical solution: a water-guided laser-water-optical coupling multi-focal-point spherical lens system, comprising a multi-focal-point spherical lens, a laser source system, a coupling cavity, a high-pressure water pump, and a processing nozzle. The focusing surface of the multi-focal-point spherical lens is composed of multiple coaxial spherical segments with different radii of curvature, intersecting and nested together, with the center of each spherical segment located on the lens's optical axis. After refraction by the composite surface, the laser beam forms an array of 2 to 8 axially spaced focal points within a water-guided jet with a diameter of 0.1–0.5 mm, dispersing the total laser energy to multiple focal points and reducing the energy density of a single focal point. The laser output from the laser source system is incident on the multi-focal-point spherical lens, and the refracted beam enters the coupling cavity and couples with a stable water column output from the high-pressure water pump to form a water-guided laser, which is finally ejected from the processing nozzle to process the workpiece.

[0007] Preferably, after the laser beam is refracted by the composite curved surface, it forms an array of 3 to 5 axially spaced focal points along the optical axis inside the light-guiding water jet with a diameter of 0.2 to 0.3 mm.

[0008] More preferably, the substrate of the multi-focus spherical lens is quartz glass with a refractive index n=1.458, a transmittance of ≥99.5% at a wavelength of 1064nm, and an outer diameter of 20mm. The focusing surface of the lens comprises three coaxial spherical segments: the first segment at the edge has a radius R1 of 50mm and a radial arc length L1 of 3mm; the second segment has a radius R2 of 30mm and a radial arc length L2 of 2.5mm; the third segment at the center has a radius R3 of 20mm and a radial arc length L3 of 2mm, intersecting with the second segment; adjacent spherical segments intersect sequentially, and the coaxiality error of each spherical segment is ≤0.005mm; the radial arc length is the length of the spherical arc segment intercepted from the center of the lens to the edge of the lens, not the chord length.

[0009] More preferably, the multi-focus spherical lens is formed by ultra-precision diamond turning, with the surface shape error of each spherical segment ≤λ / 10, where λ is the reference wavelength, λ=632.8nm, and the step height of the intersection line of the spherical segments ≤0.5μm; the focusing surface of the lens is coated with a SiO2 / TiO2 multilayer anti-reflective film, with a center wavelength reflectivity ≤0.5%, and the film is covered with a 10nm fluoride hydrophobic coating, with a water contact angle ≥110°.

[0010] Preferably, the lens is equipped with an aluminum alloy lens mount, which has a built-in positioning pin and a locking bolt. The gap between the lens and the positioning pin is ≤0.005mm, and the preload of the locking bolt is 5~8N・m. The lens mount is equipped with an X / Y axis fine adjustment knob. After calibration with a 635nm collimating laser, the coaxial deviation between the lens and the nozzle is ≤0.01mm.

[0011] Preferably, the processing nozzle is made of 304 stainless steel, with an inner diameter of 0.1mm to 0.4mm and an outlet cone angle of 30° to 75°; the high-pressure water pump outputs water pressure of 0.5 to 15MPa, a stable flow rate of 1.3 to 1.7L / min, a water column length of ≥10mm, a diameter fluctuation of ±0.01mm, and a water column vibration amplitude of ≤0.02mm.

[0012] Preferably, the diameter of each focal point formed by the lens is ≤50μm, and the single-focal energy density is controlled at 8×10⁻⁶. 7 ~1.0×10 8 W / cm 2 Below 1.2×10 8 W / cm 2 Water column explosion threshold; the system allows a maximum laser input power of 150W, which is 1.5 to 3 times the power limit of a traditional single-focus lens.

[0013] Preferably, the shape and mounting interface of the multi-focus spherical lens are completely consistent with those of the traditional single-focus lens, and it can directly replace the existing optical path focusing element without modifying the hardware structure of the laser source, high-pressure water pump, and coupling cavity.

[0014] This invention also discloses an optimization method for a water-guided laser-coupled multi-focus spherical lens system. This optimization method, which optimizes the aforementioned lens system, includes the following steps: Step S1, Lens Structure Design and Precision Machining: Select a quartz glass substrate and complete ultrasonic cleaning and drying pretreatment; determine the parameters of multiple coaxial spherical surfaces through Zemax optical simulation; use natural diamond tools for ultra-precision turning of the composite curved surface, and then coat it with an anti-reflective film and a hydrophobic coating.

[0015] Step S2, Coaxial calibration of the water-optical coupling system: Install the lens into the aluminum alloy lens holder and lock it in place; use a 635nm red collimating laser to complete the coaxial calibration of the lens and nozzle, ensuring that the deviation between the center of the light spot and the nozzle axis is ≤0.01mm; connect the high-pressure water pump and adjust the water pressure to 0.5~15MPa to obtain a low-vibration and stable water column.

[0016] Step S3, Laser Adaptation and Focus Performance Testing: Connect the fiber laser source and gradually increase the power from 50W to 150W; use a scanning camera and laser power meter to test the size and energy density of each focus point in the water column to ensure that the focus diameter is ≤50μm and the single focus energy density is lower than the gas explosion threshold.

[0017] Step S4, Processing Performance Verification and Optimization: Sapphire and silicon carbide hard and brittle materials were selected to carry out cutting and drilling tests. High-speed camera observation showed no obvious air bursts or bubbles in the water column. A coordinate measuring machine was used to detect the roundness and perpendicularity of the machined holes. The coaxiality of the lens seat and the water pressure parameters were finely adjusted according to the forming accuracy to complete the overall optimization of the system.

[0018] Preferably, in step S2, the coaxiality calibration specifically includes: after installing the lens on the lens mount, performing coaxiality calibration using a laser alignment instrument: emitting a red collimated laser, passing sequentially through the lens mount, the lens, and the nozzle, and placing a screen at a distance from the nozzle exit. Adjusting the X and Y axis fine-tuning knobs of the lens mount until the deviation between the center of the laser spot on the screen and the nozzle axis is ≤0.01mm; after fixing the lens mount, checking the coaxiality again to ensure that the deviation is stable within the allowable range.

[0019] The beneficial effects of this invention are: 1. This invention effectively avoids water column explosions and ensures stable and continuous laser transmission. By using lenses to form multiple focal points arranged in an orderly manner along the water column axis, this invention reduces the energy density of a single focal point by 30%–60%, with peak energy below the critical threshold for water column explosions. This completely eliminates faults such as water molecule vaporization causing bubbles, water column breakage, and optical path scattering loss under high-power laser action, achieving stable, low-loss long-distance laser energy transmission and significantly improving the continuity of the processing.

[0020] 2. This invention significantly expands the upper limit of equipment power and substantially improves material processing efficiency. Relying on a multi-point energy dispersion structure, this device can increase the system's allowable input laser power to 1.5 to 3 times that of traditional solutions, resulting in a 50% to 200% increase in processing efficiency for hard and brittle materials and high-hardness alloys. It can meet the needs of high-removal-volume industrial mass production scenarios such as thick plate cutting and deep hole machining, overcoming the shortcomings of traditional power reduction and time-division pulse solutions that sacrifice processing speed.

[0021] 3. This invention achieves efficient and precise optimization by dispersing energy without reducing processing accuracy. The diameter of each focal point is controlled within 50μm, and multiple points are regularly arranged along the water column axis, maintaining a processing positioning accuracy of ±0.005mm, consistent with the processing accuracy of traditional single-focal lenses. While improving laser power and processing efficiency, it can stably control workpiece edge chipping and surface roughness, eliminating the need for subsequent polishing, grinding, or other secondary processing.

[0022] 4. This invention boasts excellent overall compatibility and low equipment upgrade and modification costs. The lens shape and optical path mounting interface of this invention are fully compatible with existing commercial water-guided laser systems. There is no need to modify core hardware such as the laser, high-pressure water jet generator, and coupling cavity. Adaptation can be completed simply by directly replacing the original focusing lens. The equipment modification threshold is low, and it is compatible with the upgrade of various existing equipment.

[0023] 5. This invention has a simple structure, controllable mass production costs, and high industrialization value. Compared with improved solutions such as complex gradient refractive index lenses and multi-path beam splitting, this invention only optimizes the curved multifocal structure of the lens. The processing and manufacturing difficulty and production cost are basically the same as those of conventional single spherical lenses, which is convenient for mass production. Moreover, compared with passive optimization methods such as reducing pulse duty cycle and pressurized water path, it solves the energy concentration problem from the root of the optical path, resulting in more prominent optimization effects and significant comprehensive application advantages. Attached Figure Description

[0024] Figure 1 This is a lens structure diagram of a water-guided laser-water-optical coupling multi-focus point spherical lens system and optimization method according to the present invention; Figure 2 This is a diagram of the overall system architecture of the present invention; Figure 3 This is a 3D perspective model of the spherical lens of the present invention; Figure 4 This is a diagram of the coaxial structure of the spherical lens of the present invention. Detailed Implementation

[0025] The relevant technologies of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] like Figures 1-4 As shown, the core of the water-guided laser water-optical coupling multi-focal-point spherical lens system and optimization method in this embodiment lies in the curved surface design of the optical lens: the focusing surface of the lens is composed of multiple coaxial but different radii of intersecting spherical segments, each spherical segment nested sequentially (or arranged coaxially) around the lens optical axis, forming a "multi-spherical composite surface" structure. When the laser beam is refracted by this lens, multiple spaced focal points (focal point array) are formed along the optical axis within the light-guiding water jet, dispersing the total laser energy to multiple focal points and reducing the energy density of a single focal point, as shown in the attached figure. Figure 1 As shown.

[0028] S1: Lens structure design and parameter determination.

[0029] 1. Substrate Selection and Pretreatment: Quartz glass (refractive index n=1.458, transmittance ≥99.5%@1064nm) was selected as the lens substrate, with dimensions of: outer diameter Φ20mm and initial thickness 15mm (allowing for machining allowance). During substrate pretreatment, the substrate underwent ultrasonic cleaning (neutral detergent, water temperature 50℃, cleaning time 15min), deionized water rinsing (pressure 0.2MPa, rinsing time 5min), and drying (temperature 80℃, drying time 30min) to ensure the surface was free of oil and scratches (scratch depth ≤0.1μm).

[0030] 2. Composite Surface Parameter Design: Based on the target focusing effect (3 focal points, adjacent spacing 2mm, focal point diameter ≤50μm), the parameters of each spherical segment were determined using Zemax optical simulation software. The first spherical segment (near the incident end): radius R1 = 50 mm, arc length L1 = 3 mm (along the lens edge to the center). The second spherical segment: radius R2 = 30 mm, arc length L2 = 2.5 mm, intersecting the first spherical segment 3 mm from the lens edge. The third spherical segment (near the center): radius R3 = 20 mm, arc length L3 = 2 mm, intersecting the second spherical segment 5.5 mm from the lens edge. The center of each spherical segment is located on the lens optical axis, ensuring a coaxiality error ≤ 0.005 mm.

[0031] 3. Lens Machining Process: The curved surface is machined using an ultra-precision diamond turning machine. Specific parameters include: natural diamond cutting tools with a tip radius of 0.1 mm, a rake angle of 0°, and a clearance angle of 5°. Cutting parameters include: spindle speed of 3000 r / min, feed rate of 5 μm / r, and depth of cut of 0.5 μm / cut. Roughing is completed in 10 passes, followed by finishing in 2 passes. After machining, the surface accuracy is checked using a white light interferometer: the surface shape error of each spherical segment is ≤λ / 10 (λ=632.8 nm), and the step height of the intersection line between adjacent spherical segments is ≤0.5 μm.

[0032] 4. Lens Surface Treatment: The anti-reflective coating is applied using ion sputtering to deposit a multilayer SiO2 / TiO2 film on the focusing surface of the lens. The film thickness is designed based on the laser wavelength of 1064nm (center wavelength reflectivity ≤0.5%). For hydrophobic treatment, a fluoride hydrophobic coating (10nm thick) is applied to the film surface to ensure a water contact angle ≥110°, preventing water jets from adhering to the lens surface.

[0033] S2: Assembly of the water-optical coupling system.

[0034] 1. Nozzle and Lens Mount Design: The nozzle is made of stainless steel (model 304) with an inner diameter of Φ0.3mm and a tapered outlet (60° cone angle) to ensure a stable cylindrical jet of water (length ≥10mm, diameter fluctuation ≤±0.01mm). The lens mount is made of aluminum alloy with built-in locating pins and locking bolts. The clearance between the locating pin and the lens edge is ≤0.005mm, and the preload of the locking bolt is controlled at 5~8N·m (to prevent lens deformation under stress).

[0035] 2. Coaxiality Calibration: After mounting the lens in the lens mount, perform coaxiality calibration using a laser alignment instrument: Emits a red collimated laser (wavelength 635nm), passing it sequentially through the lens mount, lens, and nozzle. Place a screen 10mm from the nozzle exit. Adjust the X and Y axis fine-tuning knobs of the lens mount (accuracy 0.001mm / division) until the deviation between the center of the laser spot on the screen and the nozzle axis is ≤0.01mm. After fixing the lens mount, check the coaxiality again to ensure the deviation is stable within the allowable range (5 consecutive checks, maximum deviation ≤0.01mm).

[0036] 3. Water jet parameter adjustment: Connect the high-pressure water pump and nozzle, and set the water pressure parameters: initial pressure 0.5MPa. Detect the water jet flow rate using a flow sensor (accuracy ±1%), ensuring the flow rate is stable at 1.5L / min. Gradually increase the water pressure to 15MPa and observe the water jet shape (captured with a high-speed camera at 1000fps), ensuring the water jet is free of vibration and breakage (vibration amplitude ≤0.02mm).

[0037] S3: Laser and focusing system compatibility.

[0038] 1. Laser source parameter settings: Select a fiber laser with a wavelength of 532nm, a pulse width of 100ns, and a repetition frequency of 15kHz. Adjust the laser output power: Start from 50W and gradually increase to 150W, recording the parameters every 25W increase.

[0039] 2. Focus Array Detection: A laser power meter and scanning camera (MV1-D1312-80-CL-12) were used to detect the focus characteristics. A detection point was set every 0.5 mm along the optical axis within the water column, and the laser power density at each point was measured. The power densities of the three focus points were ensured to be: First focus 8 × 10⁻⁶. 7 W / cm², second focal point 1.0×10 8 W / cm², third focus 9×10 7 W / cm², all below the water column gas explosion threshold (1.2×10⁻⁶). 8W / cm²). Detection of focal point diameter: The spot size is analyzed by capturing images of the light spot with a scanning camera and using ImageJ software to ensure that the diameter of each focal point is ≤50μm (1 / e² energy distribution).

[0040] S4: Verify and optimize processing performance.

[0041] Processing Verification and Parameter Optimization: Sapphire material (5mm thickness) was selected for drilling. Processing parameters were: laser power 150W, processing speed 1mm / s, and drilling diameter 0.5mm. During processing, the water column status was observed using a high-speed camera to confirm the absence of air bursts (bubble count ≤1 / second, bubble diameter ≤0.1mm). Post-processing hole accuracy was checked: A coordinate measuring machine (model: Zeiss Contura G2) was used to measure the roundness (≤0.005mm) and perpendicularity (≤0.01mm / 10mm) of the holes to ensure they met precision machining requirements.

[0042] In summary, the water-guided laser-coupled multi-focal point spherical lens of the present invention, compared with traditional single-focal focusing lenses and various existing passive optimization schemes, disperses laser energy from the root of optical structure, effectively solves the problem of water column gas explosion under high power conditions, and has multiple advantages such as high processing efficiency, high forming accuracy, universal compatibility, and low-cost mass production.

[0043] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A water-guided laser-optical coupling multi-focal-point spherical lens system, characterized in that, This includes a multi-focus spherical lens, a laser source system, a coupling cavity, a high-pressure water pump, and a processing nozzle; The focusing surface of the multi-focal-point spherical lens is composed of multiple coaxial spherical segments with different radii of curvature, which intersect and nest together. The center of each spherical segment is located on the optical axis of the lens. After the laser beam is refracted by the composite surface, it forms an array of 2 to 8 axially spaced focal points inside the light-guiding water jet with a diameter of 0.1 to 0.5 mm, which disperses the total laser energy to multiple focal points and reduces the energy density of a single focal point. The laser source system outputs a laser beam that is incident on a multi-focus spherical lens. The refracted beam enters the coupling cavity and couples with a stable water column output by a high-pressure water pump to form a water-guided laser. Finally, the laser beam is ejected from the processing nozzle to process the workpiece.

2. The water-guided laser-optical coupling multi-focus spherical lens system according to claim 1, characterized in that, After being refracted by the composite curved surface, the laser beam forms an array of 3 to 5 axially spaced focal points along the optical axis inside the light-guiding water jet with a diameter of 0.2 to 0.3 mm.

3. The water-guided laser-water-optical coupling multi-focus spherical lens system according to claim 2, characterized in that, The substrate of the multi-focus spherical lens is quartz glass with a refractive index n=1.458, a transmittance of ≥99.5% at a wavelength of 1064nm, and an outer diameter of 20mm. The lens focusing surface comprises three coaxial spherical segments: the first spherical segment at the edge has a radius R1 of 50 mm and a radial arc length L1 of 3 mm; the second spherical segment has a radius R2 of 30 mm and a radial arc length L2 of 2.5 mm; the third spherical segment at the center has a radius R3 of 20 mm and a radial arc length L3 of 2 mm, and intersects with the second spherical segment; adjacent spherical segments intersect sequentially, and the coaxiality error of each spherical segment is ≤0.005 mm.

4. The water-guided laser-optical coupling multi-focus spherical lens system according to claim 3, characterized in that, The multi-focus spherical lens is formed by ultra-precision diamond turning, with the surface shape error of each spherical segment ≤λ / 10, where λ is the reference wavelength, and the step height of the intersection line of the spherical segment ≤0.5μm; the focusing surface of the lens is coated with a SiO2 / TiO2 multilayer anti-reflection film, with a center wavelength reflectivity ≤0.5%, and the film is covered with a 10nm fluoride hydrophobic coating, with a water contact angle ≥110°.

5. The water-guided laser-optical coupling multi-focus spherical lens system according to claim 1, characterized in that, The lens is equipped with an aluminum alloy lens mount, which has a built-in positioning pin and locking bolt. The gap between the lens and the positioning pin is ≤0.005mm, and the preload of the locking bolt is 5~8N・m. The lens mount is equipped with an X / Y axis fine adjustment knob. After calibration with a 635nm collimating laser, the coaxial deviation between the lens and the nozzle is ≤0.01mm.

6. The water-guided laser-optical coupling multi-focus spherical lens system according to claim 1, characterized in that, The processing nozzle is made of 304 stainless steel, with an inner diameter of 0.1mm to 0.4mm and an outlet cone angle of 30° to 75°; the high-pressure water pump outputs water pressure of 0.5 to 15MPa, a stable flow rate of 1.3 to 1.7L / min, a water column length of ≥10mm, a diameter fluctuation of ±0.01mm, and a water column vibration amplitude of ≤0.02mm.

7. A water-guided laser-optical coupling multi-focus spherical lens system according to claim 1, characterized in that, The diameter of each focal point formed by the lens is ≤50μm, and the energy density of a single focal point is controlled at 8×10⁻⁶. 7 ~1.0×10 8 W / cm 2 The system allows a maximum laser input power of 150W.

8. A water-guided laser-optical coupling multi-focus spherical lens system according to claim 1, characterized in that, The shape and mounting interface of the multi-focus spherical lens are completely consistent with those of the traditional single-focus lens.

9. An optimization method for a water-guided laser-water-optical coupled multi-focus spherical lens system, characterized in that, The optimization method, which optimizes the lens system according to any one of claims 1 to 8, includes the following steps: Step S1, Lens Structure Design and Precision Machining: Select quartz glass substrate and complete ultrasonic cleaning and drying pretreatment; determine the parameters of multiple coaxial spherical surfaces through Zemax optical simulation; use natural diamond tools for ultra-precision turning of composite curved surfaces, and coat them with anti-reflective film and hydrophobic coating after machining; Step S2, Coaxial calibration of the water-optical coupling system: Install the lens into the aluminum alloy lens holder and lock it in place; use a 635nm red collimating laser to complete the coaxial calibration of the lens and nozzle, ensuring that the deviation between the center of the light spot and the nozzle axis is ≤0.01mm; connect the high-pressure water pump and adjust the water pressure to 0.5~15MPa to obtain a low-vibration and stable water column; Step S3, Laser Adaptation and Focus Performance Testing: Connect the laser source and gradually increase the power; test the size and energy density of each focus point in the water column to ensure that the focus diameter is ≤50μm and the single focus energy density is lower than the gas explosion threshold. Step S4, Processing Performance Verification and Optimization: Select hard and brittle materials to conduct cutting and drilling tests, and observe that there are no obvious air bubbles in the water column; check the roundness and perpendicularity of the machined holes, and fine-tune the coaxiality of the lens seat and the water pressure parameters according to the forming accuracy to complete the overall optimization of the system.

10. The optimization method for a water-guided laser-water-optical coupled multi-focus spherical lens system according to claim 9, characterized in that, In step S2, the coaxiality calibration specifically includes: after installing the lens on the lens mount, performing coaxiality calibration using a laser alignment instrument: emitting a red collimated laser, passing through the lens mount, lens, and nozzle in sequence, and placing a screen at a distance from the nozzle outlet; adjusting the X and Y axis fine-tuning knobs of the lens mount until the deviation between the center of the laser spot on the screen and the nozzle axis is ≤0.01mm; after fixing the lens mount, checking the coaxiality again to ensure that the deviation is stable within the allowable range.

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