High-energy high-power ultraviolet femtosecond filament composite material homogeneous cutting method and system

Abstract

The invention relates to a high-energy high-power ultraviolet femtosecond filament composite material precision cutting method and system, a high-energy high-power ultraviolet femtosecond filament processing system is built, laser parameters, phase plate parameter conditions and the like are regulated and controlled, and cascade ultraviolet femtosecond filaments with ultrahigh length-diameter ratio and uniform energy distribution are generated in air through induction. The length of the light wire can be flexibly adjusted and controlled within the range of 1-60 mm, the length-diameter ratio is larger than 500, and high-speed precise cutting of the composite material with the wide thickness range can be completed under the condition that feeding machining is not needed. The long-focus deep ultraviolet femtosecond light filament can greatly enhance the laser energy absorption capacity of the composite material in the thickness direction, so that the removal depth of single scanning is remarkably increased, and the cutting speed of the composite material is greatly increased. In addition, the ultraviolet femtosecond light filaments present relatively uniform and stable energy distribution in the length direction, so that the cutting section roughness, the edge heat affected zone and the like of the composite material can be effectively reduced, and the homogeneous cutting quality and consistency are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material processing, and in particular relates to a method and system for homogeneously cutting composite materials using high-energy and high-power ultraviolet femtosecond light filaments. Background Art

[0002] Composite materials, formed by combining two or more heterogeneous components with distinct properties, can overcome the performance limitations of a single material and integrate the advantages of each component. Common composite materials include aluminum-based silicon carbide (AlSiC) and carbon fiber reinforced plastics (CFRP). AlSiC, composed of an aluminum alloy matrix and a silicon carbide ceramic reinforcement, combines low density with high strength, high thermal conductivity, low thermal expansion, and corrosion resistance, making it widely used in fields such as microelectronics, semiconductors, aerospace, and automotive manufacturing. CFRP, composed of a carbon fiber reinforcement and a resin matrix, boasts excellent properties such as light weight, high specific strength, high specific modulus, corrosion resistance, good fatigue resistance, and low thermal expansion, playing an important role in aerospace, automotive, medical equipment, and wind power generation. However, the heterogeneous components in composite materials (such as the aluminum alloy and silicon carbide in AlSiC, and the resin and carbon fiber in CFRP) differ significantly in optical, thermal, electrical, and mechanical properties, posing challenges to homogenizing these materials. Currently, mainstream traditional machining methods suffer from significant challenges such as poor processing quality, low efficiency, and severe tool wear, limiting the large-scale application of composite materials.

[0003] Femtosecond lasers, with their unique advantages of ultrashort pulse width and ultrahigh peak power, are expected to be an ideal solution for high-quality, precise, homogeneous processing of composite materials. However, due to the vastly different properties of heterogeneous composite components, their response to femtosecond lasers and their ultimate removal thresholds vary significantly. Furthermore, the Gaussian energy distribution, small focused spot size / depth of focus, and layer-by-layer processing characteristics of femtosecond lasers pose challenges in processing heterogeneous composites, such as poor quality and low efficiency. Femtosecond laser filaments are long, stable, high-energy-density laser channels formed when ultrashort, high-intensity pulses propagate through a transparent medium. By leveraging a dynamic balance between self-focusing and plasma defocusing, they possess a high aspect ratio and relatively uniform intensity distribution, promoting uniform removal of heterogeneous components, enhancing composite material removal depth and penetration speed, and improving cutting quality and efficiency. Ultraviolet femtosecond lasers, with their short action time and high peak power, have a lower filamentation threshold than near-infrared lasers, making them more effective in promoting the formation and maintenance of filaments. However, existing ultraviolet femtosecond lasers are limited by power and pulse energy, and the length and intensity of the generated light filaments are limited. They can only achieve surface etching of composite materials, and it is difficult to achieve homogeneous cutting processing of two heterogeneous materials. Summary of the Invention

[0004] To solve the above problems, the present invention provides a method and system for homogeneously cutting high-energy and high-power ultraviolet femtosecond filament composite materials, which can generate cascaded ultraviolet femtosecond filaments with ultra-long focal depth and adjustable and stable intensity.

[0005] A method for homogeneously cutting high-energy and high-power ultraviolet femtosecond light composite materials comprises the following steps:

[0006] S1: Build a UV femtosecond filament cutting system, where a phase plate with multiple concentric rings of different widths is placed in the system's optical path;

[0007] S2: generating ultraviolet femtosecond filaments in different states under different cutting system parameters, wherein the cutting system parameters include ultraviolet femtosecond laser parameters and phase plate multi-stage concentric ring distribution parameters;

[0008] S3: The length and energy distribution of the ultraviolet femtosecond filaments in different states are collected at the focus position of the scanning galvanometer by a rangefinder camera as output data. The mapping relationship between the cutting system parameters and the output data is constructed based on the machine learning method to obtain the parameter control model.

[0009] S4: Measure the thickness of the sample to be cut, and determine the cutting system parameter set that can achieve the filament length completely covering the thickness of the sample to be cut based on the parameter control model;

[0010] S5: Obtaining a processing threshold at which heterogeneous component materials in the sample to be cut can be removed synchronously and uniformly by the light filaments, and selecting a cutting system parameter whose light filament intensity is greater than the processing threshold from the cutting system parameter set obtained in S4;

[0011] S6: taking the cutting system parameter with the highest cutting evaluation index among the cutting system parameters obtained in S5 as the optimal system parameter;

[0012] S7: Setting the cutting system according to the optimal system parameters so that the cutting system performs homogeneous scanning cutting on the sample to be cut without feeding under the optimal system parameters.

[0013] Furthermore, the calculation method of the cutting evaluation index of any cutting system parameter is as follows:

[0014] A=E+MQ

[0015] Among them, A is the cutting evaluation index, E is the cutting efficiency index, Q is the cutting quality index, and M is the set weight factor.

[0016] Furthermore, the calculation method of the cutting efficiency index E is:

[0017] E=S / S max

[0018] Among them, S is the slice area that the cutting system can cut and remove in unit time under the current cutting system parameters, S max It is the maximum slice area that can be removed by the cutting system in unit time under all cutting system parameters.

[0019] Furthermore, the calculation method of the cutting quality index Q is:

[0020] Q=T / T max

[0021] Where T is the inverse of the thermal damage area of the cutting surface corresponding to the cutting system under the current cutting system parameters, T max It is the reciprocal maximum value of the thermal damage area of the cutting surface corresponding to the cutting system under all cutting system parameters.

[0022] Furthermore, the weight factor M is determined as follows:

[0023] When the cutting quality requirement is higher than the cutting efficiency requirement, M>1; when the cutting quality requirement is not higher than the cutting efficiency requirement, M≤1.

[0024] Furthermore, the distribution parameters of the multi-stage concentric rings of the phase plate include the number of concentric rings, the width of each concentric ring, the size and density of the microstructure inside each concentric ring, and the distance between the center of each concentric ring and the center of the concentric ring;

[0025] Among them, the number of concentric rings determines the number of ultraviolet femtosecond light filaments generated, the width of each concentric ring determines the length of the generated ultraviolet femtosecond light filaments, and the microstructure inside each concentric ring is a nanocolumn array with a diameter of 50-500nm and a height of 100-1000nm. The difference in the size and density of the nanocolumns determines the internal intensity of the ultraviolet femtosecond light filaments generated by the refraction and focusing of the light passing through the ring part. The distance between the center of each concentric ring and the center of the concentric ring determines the focal depth of the generated ultraviolet femtosecond light filaments.

[0026] Furthermore, the method for obtaining the processing threshold at which the heterogeneous component materials in the sample to be cut can be removed synchronously and uniformly by the filaments is as follows:

[0027] A laser processing model for heterogeneous composite materials based on a plasma-coupled dual-temperature equation was established. This processing model was used to calculate the electron density and lattice temperature distribution of the composite material after laser irradiation. Different laser fluxes irradiating the composite material corresponded to different electron density and lattice temperature distributions.

[0028] The laser flux when the lattice temperature distribution inside the material reaches the critical ablation temperature is taken as the initial processing threshold;

[0029] Using the epitaxy method to verify whether the laser flux corresponding to the initial processing threshold can synchronously and uniformly remove the heterogeneous component materials in the sample to be cut, if so, then searching for an alternative processing threshold within a set neighborhood centered on the initial processing threshold that can still synchronously and uniformly remove the heterogeneous component materials in the sample to be cut;

[0030] The maximum value among the initial processing threshold and all candidate processing thresholds is taken as the final processing threshold.

[0031] Furthermore, the parameters of the ultraviolet femtosecond laser include repetition frequency and single pulse energy, among which the repetition frequency can be adjusted in the range of 1Hz-1000KHz, and the single pulse energy can be adjusted in the range of 1-500μJ; the central wavelength of the laser beam emitted by the ultraviolet femtosecond laser is 343nm, and the single photon energy is higher than the near-infrared band. The length of the generated ultraviolet femtosecond filament can be adjusted in the range of 1-60mm, and the aspect ratio of the ultraviolet femtosecond filament is greater than 500.

[0032] Furthermore, the sample to be cut is a non-transparent heterogeneous composite material with a thickness of no more than 50 mm, wherein the non-transparent heterogeneous composite material includes an aluminum-based silicon carbide composite material and a carbon fiber reinforced composite material.

[0033] Furthermore, a high-energy and high-power ultraviolet femtosecond filament composite material homogeneous cutting system includes an ultraviolet femtosecond laser 1, a quarter-wave plate 2, a first reflector 3, a beam expander 4, a second reflector 5, a collimating aperture 6, a third reflector 7, a phase plate 8, a scanning galvanometer 9, a three-dimensional translation stage 12, and a host computer 13; wherein the phase plate 8 is an optical diffraction element having multiple concentric rings of different widths;

[0034] The laser beam emitted by the ultraviolet femtosecond laser 1 passes through the 1 / 4 wave plate 2, the first reflector 3, and the beam expander 4 in succession and is transformed into an ultraviolet femtosecond laser spot with circular polarization characteristics and an expanded size, and then is vertically introduced into the phase plate 8 through the second reflector 5 and the collimating aperture 6; the circular rings on the phase plate 8 divide the ultraviolet femtosecond laser spot into multiple discrete regional spots; after each regional spot is focused by the scanning galvanometer 9, multiple ultraviolet femtosecond filaments with uniform internal energy distribution, adjustable intensity and length between each filament, and cascaded with each other are formed at different focal depths along the optical axis direction of the scanning galvanometer 9; the ultraviolet femtosecond filaments of each cascade are incident on the sample placed on the three-dimensional translation stage 12; the host computer 13 controls the three-dimensional translation stage 12 to move according to the set program trajectory to complete the cutting of the sample.

[0035] Beneficial effects:

[0036] 1. The present invention provides a method for homogeneously cutting composite materials using high-energy, high-power ultraviolet femtosecond filaments. To meet the demand for homogeneous cutting of non-transparent heterogeneous composite materials, a high-energy, high-power ultraviolet femtosecond filament processing system is constructed. By regulating laser parameters and phase plate parameters, etc., cascaded ultraviolet femtosecond filaments with ultra-high aspect ratio and uniform energy distribution are induced in air. In other words, the present invention utilizes a phase plate to regulate and generate multi-level internally uniformly distributed filaments with adjustable focusing position and intensity, thereby generating cascaded ultraviolet femtosecond filaments with ultra-long focal depth and stable and uniform intensity distribution. The ultraviolet femtosecond filaments generated by the present invention can reach a length of 60 mm and an aspect ratio of more than 500, which is significantly higher than the focal depth of traditional Gaussian focused light spots. The ultraviolet femtosecond filaments can significantly improve the laser energy absorption capacity of the composite material in the thickness direction, greatly increasing the material removal depth and cutting penetration speed of a single scan. In addition, the ultraviolet femtosecond filaments can complete high-efficiency homogeneous cutting of thick composite materials without the need for feeding processing, significantly improving the high-speed, precise, and homogeneous cutting capability of composite materials.

[0037] 2. The present invention provides a method for homogeneously cutting composite materials using high-energy and high-power ultraviolet femtosecond light filaments. Compared with the significant energy uneven distribution characteristics of Gaussian focused spot, the ultraviolet femtosecond light filaments generated by the present invention have high internal energy density and relatively uniform and stable energy distribution along the propagation direction, which can effectively improve the homogenized removal quality and consistency of heterogeneous components of composite materials; the heat accumulation on the surface of the composite materials cut by the corresponding ultraviolet femtosecond light filaments of the present invention is significantly reduced, and it is superior to traditional Gaussian focused spot processing in key indicators such as heat affected zone, edge cracking and surface roughness.

[0038] 3. The present invention provides a high-energy, high-power ultraviolet femtosecond filament composite material homogeneous cutting system. The high-energy, high-power ultraviolet femtosecond laser used has the outstanding advantages of short action time and high peak power. Compared with the near-infrared band, the single-photon energy of the ultraviolet femtosecond laser is higher and the filament formation threshold is lower, which can more effectively promote the formation of filaments. In addition, the high single-pulse energy and high laser power of the ultraviolet femtosecond laser can effectively extend the length of the filaments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A diagram showing the cutting of thick non-transparent composite materials using ultraviolet femtosecond light. (a) and (b) are a schematic diagram and a photo of the actual process, respectively.

[0040] Figure 2 Schematic diagram comparing the focal depth and energy uniformity of the traditional Gaussian focused spot of ultraviolet femtosecond laser and the ultraviolet femtosecond laser filament.

[0041] Figure 3 Schematic diagram of generating cascaded UV femtosecond filaments for phase plate modulation.

[0042] Figure 4 This is a comparison diagram of the traditional Gaussian focused spot of ultraviolet femtosecond laser and the ultraviolet femtosecond laser filament during the cutting process, where (a) is a schematic diagram of Gaussian focused spot cutting; (b) is a schematic diagram of ultraviolet femtosecond laser filament cutting.

[0043] Figure 5 This is a diagram of the ultraviolet femtosecond light filament processing system used in the present invention.

[0044] Figure 6 This is the effect diagram of ultraviolet femtosecond light filament cutting aluminum-based silicon carbide composite material (AlSiC).

[0045] Figure 7 This is the effect diagram of ultraviolet femtosecond light cutting carbon fiber reinforced resin matrix composite (CFRP).

[0046] Among them, 1-high energy and high power ultraviolet femtosecond laser; 2-1 / 4 wave plate; 3-first reflector; 4-beam expander; 5-second reflector; 6-pinhole aperture; 7-third reflector; 8-phase plate; 9-scanning galvanometer; 10-high-speed camera; 11-sample fixture; 12-three-dimensional translation stage; 13-computer control system. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0048] Ultraviolet femtosecond lasers, with their short wavelength and high photon energy, can significantly lower the multiphoton ionization threshold of air, significantly reducing the energy requirement for filament formation and facilitating femtosecond filament generation. High pulse energy effectively increases pulse peak power, and high laser power enhances nonlinear optical effects. Both significantly enhance the self-focusing effect of ultraviolet femtosecond lasers in air, effectively increasing filament length. The proposed method and system for homogeneously cutting composite materials using high-energy, high-power ultraviolet femtosecond laser filaments can generate stable, cascaded ultraviolet femtosecond laser filaments with an ultra-long focal depth and adjustable intensity. This method effectively overcomes the significant heat-affected zone, poor cut surface flatness, and low cutting efficiency associated with conventional femtosecond Gaussian lasers, such as their uneven energy distribution, small focused spot size / depth of focus, and the need for layer-by-layer processing. It also effectively addresses the challenges of near-infrared femtosecond lasers, low-energy, low-power ultraviolet femtosecond lasers, and single-number ultraviolet femtosecond lasers, which have limited ability to cut composite materials over a wide thickness range. The proposed method demonstrates the manufacturing capability and potential for high-speed, precise, and homogeneous cutting of heterogeneous composite materials.

[0049] Based on this, the present invention provides a method for homogeneously cutting high-energy and high-power ultraviolet femtosecond light composite materials, comprising the following steps:

[0050] S1: Based on a high-energy, high-power UV femtosecond laser source and a high-damage threshold UV scanning galvanometer, a UV femtosecond filament cutting system is constructed. A phase plate with multiple concentric rings of different widths is placed in the optical path of the UV femtosecond filament cutting system.

[0051] It should be noted that the distribution parameters of the multi-stage concentric rings of the phase plate include the number of concentric rings, the width of each concentric ring, the size and density of the microstructure inside each concentric ring, and the distance between the center of each concentric ring and the center of the concentric ring;

[0052] Among them, the number of concentric rings determines the number of generated ultraviolet femtosecond light filaments, the width of each concentric ring determines the length of the generated ultraviolet femtosecond light filaments, the difference in microstructure size and density inside each concentric ring determines the internal intensity of the generated ultraviolet femtosecond light filaments, and the distance from the center of each concentric ring to the center of the concentric ring determines the focal depth of the generated ultraviolet femtosecond light filaments.

[0053] In other words, the phase plate can divide the incident original laser into regions according to a pre-designed circular distribution, and then focus it to produce multi-point cascade filaments with different focal depths and intensity distributions. Specifically, the phase plate filament control module is a high-threshold optical diffraction element with 0-5 circular rings of different widths. It can divide the incident original laser into several discrete regions. After being focused by the galvanometer, the discrete regions are focused at different positions in the direction of laser propagation. The width of the circular ring affects the energy intensity of the corresponding focal point. The wider the circular ring, the greater the intensity and length of the filaments produced by the focus. The filaments generated at different focal positions cascade, forming ultraviolet femtosecond filaments with superimposed lengths and homogenized energy.

[0054] S2: generating ultraviolet femtosecond filaments in different states under different cutting system parameters, wherein the cutting system parameters include ultraviolet femtosecond laser parameters and distribution parameters of the multi-stage concentric rings of the phase plate;

[0055] It should be noted that the parameters of the ultraviolet femtosecond laser include repetition frequency and single pulse energy, among which the repetition frequency can be adjusted in the range of 1Hz-1000kHz, and the single pulse energy can be adjusted in the range of 1-500μJ. The central wavelength of the laser beam emitted by the ultraviolet femtosecond laser is 343nm, the pulse width is ≤800fs, the maximum laser power is 80W, the maximum single pulse energy is 500μJ@160kHz, and the maximum repetition frequency is 1000kHz@80μJ. The single photon energy is higher than the near-infrared band, and the filamentation threshold is low. High single pulse energy and high laser power can promote filament extension, and multi-focus filament cascade can further improve the length and intensity uniformity of the filament. The length of the generated ultraviolet femtosecond filaments can be adjusted in the range of 1-60mm, and the aspect ratio of the ultraviolet femtosecond filaments is greater than 500. The filaments have a relatively uniform and stable energy distribution along the length direction.

[0056] S3: The length and energy distribution of the ultraviolet femtosecond filaments in different states are collected at the focus position of the scanning galvanometer by a rangefinder camera as output data. The mapping relationship between the cutting system parameters and the output data is constructed based on the machine learning method to obtain the parameter control model.

[0057] S4: Measure the thickness of the sample to be cut, and determine the cutting system parameter set that can achieve the filament length completely covering the thickness of the sample to be cut based on the parameter control model;

[0058] The sample to be cut is a non-transparent heterogeneous composite material with a thickness of no more than 50 mm, wherein the non-transparent heterogeneous composite material includes an aluminum-based silicon carbide (AlSiC) composite material and a carbon fiber reinforced composite material (CFRP).

[0059] S5: Obtaining a processing threshold at which heterogeneous component materials in the sample to be cut can be removed synchronously and uniformly by the light filaments, and selecting a cutting system parameter whose light filament intensity is greater than the processing threshold from the cutting system parameter set obtained in S4;

[0060] The method for obtaining the processing threshold at which the heterogeneous component materials in the sample to be cut can be removed synchronously and uniformly by the light filament is as follows:

[0061] A laser processing model for heterogeneous composite materials based on a plasma-coupled dual-temperature equation was established. This processing model was used to calculate the lattice temperature distribution of the composite material after laser irradiation. Different laser fluxes irradiating the composite material corresponded to different lattice temperature distributions.

[0062] The laser flux when the lattice temperature distribution inside the composite material reaches the critical ablation temperature is taken as the initial processing threshold;

[0063] Using the epitaxy method to verify whether the laser flux corresponding to the initial processing threshold can synchronously and uniformly remove the heterogeneous component materials in the sample to be cut, if so, then searching for an alternative processing threshold within a set neighborhood centered on the initial processing threshold that can still synchronously and uniformly remove the heterogeneous component materials in the sample to be cut;

[0064] The maximum value among the initial processing threshold and all candidate processing thresholds is taken as the final processing threshold.

[0065] S6: taking the cutting system parameter with the highest cutting evaluation index among the cutting system parameters obtained in S5 as the optimal system parameter;

[0066] The calculation method of the cutting evaluation index of any cutting system parameter is as follows:

[0067] A=E+MQ

[0068] Among them, A is the cutting evaluation index, E is the cutting efficiency index, Q is the cutting quality index, and M is the set weight factor.

[0069] The calculation method of cutting efficiency index E is:

[0070] E=S / S max

[0071] Among them, S is the slice area that the cutting system can cut and remove in unit time under the current cutting system parameters, S max It is the maximum slice area that can be removed by the cutting system in unit time under all cutting system parameters.

[0072] The calculation method of cutting quality index Q is:

[0073] Q=T / T max

[0074] Where T is the inverse of the thermal damage area of the cutting surface corresponding to the cutting system under the current cutting system parameters, T max It is the reciprocal maximum value of the thermal damage area of the cutting surface corresponding to the cutting system under all cutting system parameters.

[0075] The method for determining the weight factor M is:

[0076] When the cutting quality requirement is higher than the cutting efficiency requirement, M>1; when the cutting quality requirement is not higher than the cutting efficiency requirement, M≤1.

[0077] That is to say, the present invention constructs an ultraviolet femtosecond filament cutting evaluation index A=E+MQ, gives weighted comprehensive consideration to the cutting efficiency index E and the quality index Q of the composite material processing structure, and assigns values according to the differentiated requirements of composite material manufacturing efficiency and quality; using the ultraviolet femtosecond laser parameters obtained in step S5, the composite material is scanned and cut without feeding to obtain the highest value of the cutting evaluation index A, thereby determining the optimal parameters.

[0078] S7: Setting the cutting system according to the optimal system parameters so that the cutting system performs homogeneous scanning cutting on the sample to be cut without feeding under the optimal system parameters.

[0079] It can be seen that the present invention is suitable for homogeneous cutting of various types of composite materials with a wide thickness range. It uses a high-energy, high-power ultraviolet femtosecond laser combined with phase plate control, coordinated with scanning galvanometer focusing and processing path control, and utilizes the self-focusing effect and plasma defocusing effect. The two are dynamically balanced to form long-distance laser filaments. By changing the laser parameters and phase plate parameters, the length and energy distribution of the femtosecond filaments can be controlled, thereby achieving efficient and precise homogeneous cutting of various composite materials, especially thicker materials; the schematic diagram and actual photos of ultraviolet femtosecond filament cutting of composite materials are shown in the figure. Figure 1 shown.

[0080] Furthermore, the ultraviolet femtosecond filament cutting system constructed by the present invention includes an ultraviolet femtosecond laser 1, a quarter-wave plate 2, a first reflector 3, a beam expander 4, a second reflector 5, a collimating aperture 6, a third reflector 7, a phase plate 8, a scanning galvanometer 9, a camera 10, a sample holder 11, a three-dimensional translation stage 12, and a host computer 13; wherein the phase plate 8 is an optical diffraction element having multiple concentric rings of different widths;

[0081] The laser beam emitted by the ultraviolet femtosecond laser 1 passes through the 1 / 4 wave plate 2, the first reflector 3, and the beam expander 4 in succession, and is transformed into an ultraviolet femtosecond laser spot with circular polarization characteristics and an expanded size. Then, it is vertically introduced into the phase plate 8 through the second reflector 5 and the collimating aperture 6. The circular rings on the phase plate 8 divide the ultraviolet femtosecond laser spot into a plurality of discrete regional spots. After the regional spots are focused by the scanning galvanometer 9, the internal energy is uniformly distributed at different focal depths along the optical axis of the scanning galvanometer 9, and the intensity and length of each filament are adjustable and mutually leveled. The invention relates to a method for cutting a sample of an object to be cut, comprising: connecting a plurality of ultraviolet femtosecond filaments with an ultra-high aspect ratio; the clamp 11 is used to fix the sample to be cut on the three-dimensional translation stage 12; the ultraviolet femtosecond filaments of each stage are incident on the sample placed on the three-dimensional translation stage 12; the host computer 13 controls the three-dimensional translation stage 12 to move it according to the set program trajectory to complete the cutting of the sample; the camera 10 is used to perform real-time imaging and monitoring of the cutting process of the sample; the host computer 13 is also used to adjust the laser parameters of the femtosecond laser and is connected to the camera 10 for lateral real-time imaging and monitoring.

[0082] It should be noted that if Figure 2 As shown in the figure, the high-energy and high-power ultraviolet femtosecond laser light source used in the present invention has higher single-photon energy in the ultraviolet band and lower filament formation threshold than in the near-infrared band, which can more effectively promote the formation and maintenance of filaments. At the same time, the high single-pulse energy of the ultraviolet femtosecond laser can effectively extend the length of the filaments, and the high-power characteristics can greatly increase the cutting depth and penetration speed. In addition, the phase plate can be further used to generate cascaded filaments with multi-level intensity and adjustable focus position. The schematic diagram of the generation of cascaded filaments is shown in the figure. Figure 3 Compared with Gaussian focused spot, ultraviolet femtosecond light filaments have longer focal depth and better energy uniformity and stability over a long range. Figure 4 As shown, when ultraviolet femtosecond light is used to cut thick non-transparent materials, since the focal depth is not less than the material thickness, the present invention does not require feeding and layer-by-layer scanning, and can achieve efficient and homogeneous cutting of multiple types of non-transparent composite materials with a wide thickness range.

[0083] The following describes in detail the method for homogeneously cutting composite materials using high-energy and high-power ultraviolet femtosecond light, taking aluminum-based silicon carbide and carbon fiber-reinforced resin-based composite materials as examples of samples to be cut.

[0084] Example 1, ultraviolet femtosecond light filament aluminum-based silicon carbide high-speed precision homogeneous slicing, comprising the following steps:

[0085] Step 1.1: Build a UV femtosecond filament processing system based on a high-energy, high-power UV femtosecond laser source and a high-damage threshold UV scanning galvanometer.

[0086] like Figure 5 As shown, the ultraviolet femtosecond filament processing system includes a high-energy and high-power ultraviolet femtosecond laser 1, a 1 / 4 wave plate 2, a first reflector 3, a beam expander 4, a second reflector 5, a pinhole aperture 6, a third reflector 7, a phase plate 8, a scanning galvanometer 9, a high-speed camera 10, a sample fixture 11, a three-dimensional translation stage 12, and a computer control system 13.

[0087] The laser beam emitted by a high-energy, high-power UV femtosecond laser 1 passes through a quarter-wave plate 2 and a beam expander 4, producing a high-quality UV femtosecond laser spot with circular polarization and an expanded size. It then passes through a collimating aperture 6 and is vertically guided to a phase plate 8. It then enters the light inlet of a scanning galvanometer system 9, where it is focused in air to form cascaded UV femtosecond filaments with an ultra-high aspect ratio and uniform energy distribution. A fixture 11 secures the aluminum-based silicon carbide sample to be processed. A computer control system 13 regulates the UV femtosecond laser parameters and controls a three-dimensional translation stage 12 to move along a programmed trajectory. A high-speed camera 10 is connected for real-time lateral imaging and monitoring.

[0088] The laser can output ultraviolet femtosecond laser pulses with a central wavelength of 343nm, a pulse width of 650fs, a maximum laser power of 80W, a maximum single pulse energy of 500μJ@160kHz, and a maximum repetition frequency of 1000kHz@80μJ.

[0089] Step 1.2: Install a phase plate filament control module consisting of multiple concentric rings of different widths in the optical path.

[0090] Step 1.3: Set up a paraxial UV high-speed imaging module and observe the formation state of UV femtosecond filaments at the galvanometer focusing position. Based on the UV femtosecond laser parameters and the multi-stage circular distribution parameters of the phase plate, generate cascaded UV femtosecond filaments and collect a data set of their length and intensity distribution. Build an input-output mapping relationship based on machine learning methods, and establish a UV femtosecond filament parameter prediction and control model.

[0091] Among them, the phase plate filament control module is a high-threshold optical diffraction element with 0-5 circular rings of different widths; the ultraviolet femtosecond laser repetition frequency can be controlled in the range of 1Hz-1000kHz, and the single pulse energy can be controlled in the range of 1-500μJ.

[0092] Step 1.4: The thickness of the aluminum-based silicon carbide sample to be processed is measured to be 25 mm and the area is 25 mm × 15 mm. Based on the UV femtosecond filament parameter prediction and control model established in step 1.3, determine the phase plate parameter conditions and UV femtosecond laser parameter set that can achieve the filament length completely covering the thickness of the aluminum-based silicon carbide sample.

[0093] Step 1.5: Based on the plasma-coupled dual-temperature equation, a laser processing model for heterogeneous components of composite materials is established and the material processing threshold is calculated. The epitaxial method is used to verify the threshold at which the heterogeneous component materials in the aluminum-based silicon carbide sample can be effectively and synchronously and homogeneously removed. Based on the ultraviolet femtosecond filament parameter prediction and control model established in step 1.3, the parameter set obtained in step 1.4 is further determined to achieve a parameter set that can generate a filament intensity greater than the removal threshold of all heterogeneous components.

[0094] Step 1.6: Weightedly consider the cutting efficiency index E and quality index Q of the aluminum-based SiC processing structure to construct a UV femtosecond laser cutting evaluation index A = E + MQ, where M is the weighting factor. This index is assigned based on the differentiated requirements for composite material manufacturing efficiency and quality. Using the UV femtosecond laser parameter set obtained in Step 1.5, perform feed-free scanning cutting of aluminum-based SiC samples to obtain the highest value for the cutting evaluation index A, thereby determining the optimal parameters.

[0095] In this embodiment, the thickness of the aluminum-based silicon carbide sample is relatively large, and a higher cutting efficiency is expected, so M is assigned a value of 0.7.

[0096] The final parameter combination is: laser power 50W, single pulse energy 200μJ, repetition frequency 250kHz, phase plate with three discrete rings, and the measured filament length is 35mm; during scanning and cutting, the scanning speed is 200mm / s, the scanning length is 10mm, and the scanning path is 15 parallel straight lines with an interval of 30μm.

[0097] The beneficial effects of this embodiment are: Figure 6 At present, the mainstream cutting methods for aluminum-based silicon carbide materials are diamond wire cutting, water-guided laser cutting and other methods. Since the reinforcing phase in the composite material is silicon carbide particles with a particle size of 5-20μm, it is difficult to cut and it is difficult to achieve efficient and high-quality cutting effects. For a 25mm thick aluminum-based silicon carbide sample, this embodiment records that it is completely cut through after scanning for about 200s, and the cutting quality is within 15μm of the edge heat-affected zone. The slices are complete and burr-free, and the surface of the slices is not affected by dust deposition or other heat accumulation, which can effectively protect the integrity of the device. This embodiment is widely used in chip packaging, photovoltaic manufacturing and other fields.

[0098] Example 2: High-speed, high-power ultraviolet femtosecond light filament carbon fiber reinforced resin-based composite material (CFRP) high-speed, precise, and homogeneous cutting, comprising the following steps:

[0099] Step 2.1: Build a UV femtosecond filament processing system based on a high-energy, high-power UV femtosecond laser source and a high-damage threshold UV scanning galvanometer.

[0100] like Figure 5 As shown, the ultraviolet femtosecond filament processing system includes a high-energy and high-power ultraviolet femtosecond laser 1, a 1 / 4 wave plate 2, a first reflector 3, a beam expander 4, a second reflector 5, a pinhole aperture 6, a third reflector 7, a phase plate 8, a scanning galvanometer 9, a high-speed camera 10, a sample fixture 11, a three-dimensional translation stage 12, and a computer control system 13.

[0101] The laser beam emitted by a high-energy, high-power UV femtosecond laser 1 passes through a quarter-wave plate 2 and a beam expander 4, producing a high-quality UV femtosecond laser spot with circular polarization and an expanded size. It then passes through a collimating aperture 6 and is vertically guided into a phase plate 8. It then enters the light inlet of a scanning galvanometer system 9, where it is focused in air to form cascaded UV femtosecond filaments with an ultra-high aspect ratio and uniform energy distribution. A fixture 11 secures the CFRP sample to be processed. A computer control system 13 regulates the UV femtosecond laser parameters and controls a three-dimensional translation stage 12 to move along a programmed trajectory. A high-speed camera 10 is connected for real-time lateral imaging and monitoring.

[0102] The laser can output ultraviolet femtosecond laser pulses with a central wavelength of 343nm, a pulse width of 350fs, a maximum laser power of 20W, a maximum single pulse energy of 200μJ@100kHz, and a maximum repetition frequency of 500kHz@40μJ.

[0103] Step 2.2: Install a phase plate filament control module consisting of multiple concentric rings of different widths in the optical path.

[0104] Step 2.3: Set up a paraxial UV high-speed imaging module to observe the formation state of UV femtosecond filaments at the galvanometer focusing position. Based on the UV femtosecond laser parameters and the multi-stage circular distribution parameters of the phase plate, generate cascaded UV femtosecond filaments and collect a data set of their length and intensity distribution. Based on the machine learning method, construct an input-output mapping relationship and establish a UV femtosecond filament parameter prediction and control model.

[0105] Among them, the phase plate filament control module is a high-threshold optical diffraction element with 0-5 circular rings of different widths; the ultraviolet femtosecond laser repetition frequency can be controlled in the range of 1Hz-500kHz, and the single pulse energy can be controlled in the range of 1-200μJ.

[0106] Step 2.4: The thickness of the CFRP sample to be processed is measured to be 1 mm and the area is 25 mm × 15 mm. Based on the UV femtosecond filament parameter prediction and control model established in Step 2.3, determine the phase plate parameter conditions and UV femtosecond laser parameter set that can achieve the filament length completely covering the thickness of the CFRP sample.

[0107] Step 2.5: Based on the plasma-coupled dual-temperature equation, a laser processing model for heterogeneous components of composite materials is established and the material processing threshold is calculated. The epitaxy method is used to verify the threshold at which heterogeneous component materials in the CFRP sample can be effectively and synchronously and homogeneously removed. Based on the UV femtosecond filament parameter prediction and control model established in step 2.3, the parameter set obtained in step 2.4 is further determined to achieve a filament intensity greater than the removal threshold for all heterogeneous components.

[0108] Step 2.6: Weighted and comprehensive considerations are given to the cutting efficiency index E and quality index Q of the CFRP fabricated structure. A UV femtosecond laser cutting evaluation index A = E + MQ is constructed, with M being the weighting factor. This index is assigned based on the differentiated requirements for composite material manufacturing efficiency and quality. Using the UV femtosecond laser parameter set obtained in Step 2.5, a feed-free scanning cut of the CFRP sample is performed to obtain the highest value for the cutting evaluation index A, thereby determining the optimal parameters.

[0109] In this embodiment, the quality requirements of the CFRP sample are high and low thermal damage is expected, so M is assigned a value of 1.4.

[0110] The final parameter combination was determined as follows: laser power 16W, single pulse energy 160μJ, repetition frequency 100kHz, phase plate with a single circular ring, and the measured filament length was 5mm; during scanning and cutting, the scanning speed was 800mm / s, the scanning length was 10mm, and the scanning path was 5 parallel straight lines with an interval of 40μm.

[0111] The beneficial effects of this embodiment are: Figure 7 For a 1mm thick CFRP sample, this example achieved complete penetration after 8.5 seconds of scanning, with a cut quality of less than 5μm in the heat-affected zone at the edge. This achieves high-speed, high-quality, and precise homogeneous cutting of CFRP materials without the need for additional pre- or post-processing, and has broad applications in aerospace, rail transportation, and other fields.

[0112] In summary, in response to the cutting needs of non-transparent heterogeneous composite materials, the present invention builds a high-energy and high-power ultraviolet femtosecond filament processing system, adjusts the laser parameters and phase plate parameter conditions, and induces the generation of cascaded ultraviolet femtosecond filaments with ultra-high aspect ratio and uniform energy distribution in the air. The filament length can be flexibly adjusted in the range of 1-60mm, and the aspect ratio is greater than 500. Without the need for feed processing, high-speed, precise, and homogeneous cutting of composite materials with a wide thickness range can be completed, such as aluminum-based silicon carbide, carbon fiber reinforced composite materials, etc. Long-focus deep ultraviolet femtosecond filaments can greatly enhance the composite material's ability to absorb laser energy in the thickness direction, significantly increasing the removal depth of a single scan and greatly improving the cutting speed of the composite material. In addition, the ultraviolet femtosecond filament presents a relatively uniform and stable energy distribution along the length direction, which can effectively reduce the roughness of the cut section of the composite material and the edge heat-affected zone, and significantly improve the homogenized cutting quality and consistency. The method of the present invention demonstrates the manufacturing capability and application prospects of high-speed, precise, and homogeneous cutting of heterogeneous composite materials.

[0113] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may of course make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for homogeneously cutting high-energy and high-power ultraviolet femtosecond light composite materials, characterized in that: The following steps are involved: S1: Build a UV femtosecond filament cutting system, where a phase plate with multiple concentric rings of different widths is placed in the system's optical path; S2: generating ultraviolet femtosecond filaments in different states under different cutting system parameters, wherein the cutting system parameters include ultraviolet femtosecond laser parameters and phase plate multi-stage concentric ring distribution parameters; S3: The length and energy distribution of the ultraviolet femtosecond filaments in different states are collected at the focus position of the scanning galvanometer by a rangefinder camera as output data. The mapping relationship between the cutting system parameters and the output data is constructed based on the machine learning method to obtain the parameter control model. S4: Measure the thickness of the sample to be cut, and determine the cutting system parameter set that can achieve the filament length completely covering the thickness of the sample to be cut based on the parameter control model; S5: Obtaining a processing threshold at which heterogeneous component materials in the sample to be cut can be removed synchronously and uniformly by the light filaments, and selecting a cutting system parameter whose light filament intensity is greater than the processing threshold from the cutting system parameter set obtained in S4; S6: taking the cutting system parameter with the highest cutting evaluation index among the cutting system parameters obtained in S5 as the optimal system parameter; S7: Setting the cutting system according to the optimal system parameters so that the cutting system performs homogeneous scanning cutting on the sample to be cut without feeding under the optimal system parameters.

2. The method for homogeneously cutting high-energy and high-power ultraviolet femtosecond light composite materials according to claim 1, characterized in that: The calculation method of the cutting evaluation index of any cutting system parameter is as follows: A=E+MQ Among them, A is the cutting evaluation index, E is the cutting efficiency index, Q is the cutting quality index, and M is the set weight factor.

3. The method for homogeneously cutting high-energy and high-power ultraviolet femtosecond light composite materials according to claim 2, characterized in that: The calculation method of cutting efficiency index E is: E=S / S max Among them, S is the slice area that the cutting system can cut and remove in unit time under the current cutting system parameters, S max It is the maximum slice area that can be removed by the cutting system in unit time under all cutting system parameters.

4. The method for precision cutting of high-energy and high-power ultraviolet femtosecond light composite materials according to claim 2, characterized in that: The calculation method of cutting quality index Q is: Q=T / T max Where T is the inverse of the thermal damage area of the cutting surface corresponding to the cutting system under the current cutting system parameters, T max It is the reciprocal maximum value of the thermal damage area of the cutting surface corresponding to the cutting system under all cutting system parameters.

5. The method for homogeneously cutting high-energy and high-power ultraviolet femtosecond light composite materials according to claim 2, characterized in that: The method for determining the weight factor M is: When the cutting quality requirement is higher than the cutting efficiency requirement, M>1; when the cutting quality requirement is not higher than the cutting efficiency requirement, M≤1.

6. The method for homogeneously cutting high-energy and high-power ultraviolet femtosecond light composite materials according to claim 1, characterized in that: The distribution parameters of the multi-stage concentric rings of the phase plate include the number of concentric rings, the width of each concentric ring, the size and density of the microstructure inside each concentric ring, and the distance between the center of each concentric ring and the center of the concentric ring. Among them, the number of concentric rings determines the number of ultraviolet femtosecond light filaments generated, the width of each concentric ring determines the length of the generated ultraviolet femtosecond light filaments, and the microstructure inside each concentric ring is a nanocolumn array with a diameter of 50-500nm and a height of 100-1000nm. The difference in the size and density of the nanocolumns determines the internal intensity of the ultraviolet femtosecond light filaments generated by the refraction and focusing of the light passing through the ring part. The distance between the center of each concentric ring and the center of the concentric ring determines the focal depth of the generated ultraviolet femtosecond light filaments.

7. The method for homogenizing and cutting high-energy and high-power ultraviolet femtosecond light composite materials according to claim 1, wherein: The method for obtaining the processing threshold at which the heterogeneous component materials in the sample to be cut can be removed synchronously and uniformly by the filament is: A laser processing model for heterogeneous composite materials based on a plasma-coupled dual-temperature equation was established. This processing model was used to calculate the electron density and lattice temperature distribution of the composite material after laser irradiation. Different laser fluxes irradiating the composite material corresponded to different electron density and lattice temperature distributions. The laser flux when the lattice temperature distribution inside the material reaches the critical ablation temperature is taken as the initial processing threshold; Using the epitaxy method to verify whether the laser flux corresponding to the initial processing threshold can synchronously and uniformly remove the heterogeneous component materials in the sample to be cut, if so, then searching for an alternative processing threshold within a set neighborhood centered on the initial processing threshold that can still synchronously and uniformly remove the heterogeneous component materials in the sample to be cut; The maximum value among the initial processing threshold and all candidate processing thresholds is taken as the final processing threshold.

8. The method for homogeneously cutting high-energy and high-power ultraviolet femtosecond light composite materials according to claim 1, characterized in that: The parameters of the ultraviolet femtosecond laser include repetition frequency and single pulse energy. The repetition frequency can be adjusted in the range of 1Hz-1000KHz, and the single pulse energy can be adjusted in the range of 1-500μJ. The central wavelength of the laser beam emitted by the ultraviolet femtosecond laser is 343nm, and the single photon energy is higher than the near-infrared band. The length of the generated ultraviolet femtosecond filament can be adjusted in the range of 1-60mm, and the aspect ratio of the ultraviolet femtosecond filament is greater than 500.

9. The method for homogeneously cutting high-energy and high-power ultraviolet femtosecond light composite materials according to claim 1, characterized in that: The sample to be cut is a non-transparent heterogeneous composite material with a thickness of no more than 50 mm, wherein the non-transparent heterogeneous composite material includes an aluminum-based silicon carbide composite material and a carbon fiber reinforced composite material.

10. A high energy and high power ultraviolet femtosecond light composite material homogeneous cutting system, characterized in that: The invention comprises an ultraviolet femtosecond laser (1), a quarter-wave plate (2), a first reflector (3), a beam expander (4), a second reflector (5), a collimating aperture (6), a third reflector (7), a phase plate (8), a scanning galvanometer (9), a three-dimensional translation stage (12), and a host computer (13); wherein the phase plate (8) is an optical diffraction element having a plurality of concentric rings of different widths; The laser beam emitted by the ultraviolet femtosecond laser (1) is transformed into an ultraviolet femtosecond laser spot with circular polarization characteristics and expanded size after passing through a quarter wave plate (2), a first reflector (3), and a beam expander (4), and then is vertically introduced into a phase plate (8) through a second reflector (5) and a collimating aperture (6); each circular ring on the phase plate (8) divides the ultraviolet femtosecond laser spot into a plurality of discrete regional spots; after each regional spot is focused by a scanning galvanometer (9), a plurality of ultraviolet femtosecond filaments with uniform internal energy distribution, adjustable intensity and length between each filament, and mutually cascaded are formed at different focal depths along the optical axis direction of the scanning galvanometer (9); each cascaded ultraviolet femtosecond filament is incident on a sample placed on a three-dimensional translation stage (12); a host computer (13) controls the three-dimensional translation stage (12) to move according to a set program trajectory to complete the cutting of the sample.

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