A femtosecond laser-based adaptive cutting method and system

Abstract

The present application relates to a kind of adaptive cutting method and system based on femtosecond laser applied to the technical field of laser precision machining, method includes: the thickness parameter of the material to be cut is obtained and compared with predetermined threshold;If thickness is greater than threshold, control optical system directs laser to beisel optical system and carries out longitudinal cutting;If thickness is less than or equal to threshold, it is guided to time compression and spatial dispersion system and carries out transverse cutting.System includes femtosecond laser, longitudinal and transverse cutting optical system, beisel optical system, time compression and spatial dispersion system and controller.The present application solves the technical contradiction that single system cannot consider longitudinal cutting of thick material and transverse precision cutting of thin material by integrating two sets of optical systems and adaptive switching, realizes high-quality "one-key" processing of brittle hard material from micrometer level to centimeter level thickness.

Description

TECHNICAL FIELD

[0001] The present application relates to a cutting method and system, in particular to a self-adaptive cutting method and system based on femtosecond laser applied to the field of laser precision machining technology. BACKGROUND

[0002] Laser cutting technology has been widely used in brittle and hard material processing field due to its high precision, non-contact and other advantages. Femtosecond laser can realize "cold processing" and significantly reduce the heat affected zone due to its ultra-short pulse and ultra-high peak power characteristics, becoming an ideal tool for precision machining.

[0003] However, the existing femtosecond laser cutting technology has significant limitations when facing different surface types and thicknesses of brittle and hard materials:

[0004] Longitudinal cutting problem: for materials with large thickness (such as >100 μm), the traditional focused Gaussian beam has uneven energy distribution along the depth direction, which easily leads to overburning at the top and incomplete cutting at the bottom of the material, and large cutting taper and poor cutting quality.

[0005] Transverse cutting problem: for thin or high-precision edge materials (such as thickness ≤10 μm), although femtosecond laser has small heat affected zone, the traditional method still has hundreds of microns of heat affected zone, which easily leads to cracking of thin brittle materials. At the same time, spatial dispersion and temporal broadening occur during laser pulse transmission and focusing, leading to spot distortion and peak power reduction inside the material, resulting in insufficient cutting precision and efficiency.

[0006] Lack of versatility and flexibility: the existing technical solutions have single function, and a set of system is usually optimized for a specific thickness or cutting direction. When the thickness of the processed object changes, the equipment needs to be replaced or the optical path needs to be adjusted complexly, which cannot realize the intelligent adaptive cutting mode of "one-key switching" according to the thickness requirement of the material, and the equipment has poor versatility and is complicated to operate.

[0007] Therefore, there is an urgent need in the art for a high-efficiency and high-precision femtosecond laser cutting solution that can adapt to different thickness materials and balance longitudinal deep cutting and transverse precision cutting. SUMMARY

[0008] The present application aims to overcome the shortcomings of the prior art and provide a self-adaptive cutting method and system based on femtosecond laser, which aims to solve the technical contradiction that the prior art cannot adaptively select the optimal cutting mode according to the material thickness, and realize high-quality and high-efficiency "one-key" invisible cutting from micron-level thin sheets to centimeter-level thick brittle and hard materials.

[0009] To achieve the above purpose, in a first aspect, the present application provides a self-adaptive cutting method based on femtosecond laser, comprising the following steps:

[0010] acquire a thickness parameter of the material to be cut, and compare the thickness parameter with a predetermined threshold value;

[0011] if the thickness parameter is greater than the predetermined threshold value, control the longitudinal and lateral cutting optical system to direct the femtosecond laser beam to a Bessel optical system; the Bessel optical system converts the beam into a Bessel beam by means of a conical lens, and focuses the Bessel beam into the material by means of a lens group for longitudinal cutting;

[0012] if the thickness parameter is less than or equal to the predetermined threshold value, control the longitudinal and lateral cutting optical system to direct the femtosecond laser beam to a time compression and spatial dispersion system; the time compression and spatial dispersion system performs spatial dispersion on the beam by means of a reflective grating, and reflects the dispersed beam back to the reflective grating by means of a mirror pair composed of a first mirror and a second mirror for collimation, and finally time and spatially focuses the collimated parallel spectrum into the material for lateral cutting.

[0013] Preferably, the predetermined threshold value is 10 μm.

[0014] Preferably, the lens group is a 4f lens system composed of a first focusing mirror and a second focusing mirror, which is used to adjust the focal depth and spot diameter of the Bessel beam.

[0015] Preferably, in the time compression and spatial dispersion system, time dispersion compensation is performed on the collimated parallel spectrum to re-synchronize different wavelength components in time.

[0016] Preferably, in the time compression and spatial dispersion system, the optical path between the first mirror and the second mirror and the reflective grating is adjusted by driving an axial displacement platform to achieve time dispersion compensation.

[0017] The time dispersion compensation is used to achieve time and spatial focusing of the laser pulse when focused.

[0018] As a further improvement of the present application, during the cutting process, the following steps are further included:

[0019] real-time acquisition of a monitoring signal reflecting the cutting quality;

[0020] comparison of the monitoring signal with a preset quality threshold value;

[0021] if the monitoring signal is worse than the quality threshold value, control the longitudinal and lateral cutting optical system to dynamically switch the cutting mode.

[0022] Preferably, the monitoring signal is a laser-induced plasma spectrum signal.

[0023] Preferably, the monitoring signal being worse than the quality threshold value means that the continuous background spectrum intensity representing incomplete vaporization of the material is lower than a preset intensity threshold value.

[0024] Preferably, the dynamic switching of the cutting mode is temporarily switching from the current main cutting mode to another fine cutting mode, and switching back to the main cutting mode after the fine cutting is completed.

[0025] Preferably, the main cutting mode and the fine cutting mode correspond to two different cutting modes provided by the Bessel optical system and the time compression and spatial dispersion system respectively.

[0026] In another aspect, the application provides a femtosecond laser-based adaptive cutting system, comprising:

[0027] a femtosecond laser;

[0028] a longitudinal and lateral cutting optical system, whose optical input end is connected to the femtosecond laser, and whose optical output end is switchably connected to the Bessel optical system or the time compression and spatial dispersion system;

[0029] a Bessel optical system, comprising a conical lens and a lens group arranged in sequence along the optical path;

[0030] a time compression and spatial dispersion system, comprising a laser beam expander, a reflection grating, and first and second reflection mirrors arranged perpendicularly to each other, arranged in sequence along the optical path;

[0031] a controller, signal-connected to the longitudinal and lateral cutting optical system, configured to receive a thickness parameter, and send a switching instruction to the longitudinal and lateral cutting optical system according to the comparison result of the thickness parameter and a predetermined threshold.

[0032] Preferably, the longitudinal and lateral cutting optical system is an electrically controllable optical switch or an optical path switcher.

[0033] Preferably, the lens group is a 4f lens system.

[0034] Preferably, the time compression and spatial dispersion system further comprises an axial displacement platform, and the first and second reflection mirrors are installed on the axial displacement platform.

[0035] Preferably, the time compression and spatial dispersion system further comprises a laser focusing system and a third reflection mirror.

[0036] The third reflection mirror is used to reflect the parallel spectrum emitted from the self-reflection grating to the laser focusing system.

[0037] Preferably, the adaptive cutting system further comprises a thickness measurement sensor for automatically obtaining the thickness parameter of the material to be cut.

[0038] As a further improvement of the application, the adaptive cutting system further comprises a cutting quality real-time monitoring module, which is signal-connected to the controller.

[0039] The controller is further configured to:

[0040] receiving a monitoring signal reflecting the cutting quality from the cutting quality real-time monitoring module;

[0041] comparing the monitoring signal with a preset quality threshold;

[0042] if the monitoring signal is worse than the quality threshold, generating a dynamic switching instruction and sending it to the longitudinal-transverse cutting optical system.

[0043] Preferably, the cutting quality real-time monitoring module is a spectrum monitoring unit integrated in the laser transmission light path from the femtosecond laser to the material to be cut through a spectroscope, for collecting the plasma spectrum signal at the machining point.

[0044] Compared with the prior art, the present application has the following beneficial effects:

[0045] The present application breaks through the narrow processing range of a single system by intelligently selecting the best cutting mode through the closed-loop control of "perception-judgment-switching", and realizes seamless coverage of the full thickness range from microns to centimeters. For thick materials, the long focal depth and non-diffraction characteristics of the Bessel beam ensure uniform energy in the full depth of the cutting path, good verticality of the cut, no taper, and resistance to internal defect interference by virtue of the self-repairing feature. For thin materials, the heat-affected zone is reduced to sub-micron level through the time-space double focusing technology, with smooth edges and no cracks, and extremely high cutting precision. Only the material thickness needs to be input by the user or automatically acquired by the system, and "one-key switching" can be realized without the need to replace the equipment or perform complex optical path re-adjustment, which greatly reduces the equipment cost, maintenance cost and technical threshold of the operator, and provides an efficient and economical solution for the diversification and large-scale processing of brittle and hard materials.

[0046] Furthermore, the present application also has the ability of "online diagnosis and self-repairing" by introducing real-time quality feedback and dynamic switching. It can actively detect and compensate for insufficient cutting depth and microscopic defects such as micro-cracks caused by material micro-uniformity, thereby significantly improving the consistency and yield of the entire batch of workpiece processing quality. In particular, this ability can intelligently cope with the processing challenges of "critical thickness" materials, effectively widening the process window for stable processing by dynamically integrating the advantages of the two cutting modes. In addition, the real-time acquisition of physical signals also lays a solid foundation for the accumulation of process data and subsequent process optimization. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is the structure block diagram of the adaptive cutting system in the first embodiment of the present application;

[0048] Figure 2 is the optical path schematic diagram of the Bessel optical system in the first embodiment of the present application;

[0049] Figure 3 Fig. 1 is a schematic diagram of an optical path of a time compression and spatial dispersion system in a first embodiment of the present application;

[0050] Figure 4 Fig. 2 is a flow chart of an adaptive cutting method in the first embodiment of the present application;

[0051] Figure 5 Fig. 3 is a structural block diagram of an adaptive cutting system in a second embodiment of the present application;

[0052] Figure 6 Fig. 4 is a flow chart of an adaptive cutting method in the second embodiment of the present application.

[0053] Explanation of reference numerals in the drawings:

[0054] 1, femtosecond laser; 2, Bessel optical system; 21, conical lens; 22, lens group; 3, time compression and spatial dispersion system; 31, laser beam expander; 32, reflective grating; 33, first mirror; 34, second mirror; 35, axial displacement platform; 36, third mirror; 37, laser focusing system. DETAILED DESCRIPTION

[0055] The two embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be noted that the specific embodiments described herein are merely intended to explain the present application, and are not intended to limit the protection scope of the present application.

[0056] First embodiment:

[0057] Figures 1-3 A femtosecond laser-based adaptive cutting system is shown, which mainly comprises a femtosecond laser 1, a longitudinal and lateral cutting optical system, a Bessel optical system 2, a time compression and spatial dispersion system 3, and a controller.

[0058] The femtosecond laser 1 is used to generate a femtosecond laser beam with ultra-short pulses. As a preferred embodiment, a commercial femtosecond laser with a central wavelength in the infrared band of 1030 nm or 1053 nm and a pulse width of about 100 femtoseconds can be used.

[0059] In order to realize automatic acquisition of the thickness parameter, as a preferred embodiment, the adaptive cutting system further comprises a thickness measurement sensor. The sensor is preferably a non-contact laser ranging sensor or a spectral confocal displacement sensor, which is installed near the sample table and makes its measurement beam vertically incident to the to-be-measured region of the material to be cut. Before the processing flow starts or after the material is replaced, the controller can drive the sensor or the sample table to perform scanning measurement, thereby automatically and accurately obtaining the thickness information of the material. The thickness parameter can also be manually input by the operator through the human-machine interface, and the system supports both automatic and manual modes to adapt to different application scenarios.

[0060] The longitudinal and transverse cutting optical system is the core of realizing the adaptive switching of the optical path. In a specific embodiment, the system can use a translatable mirror group driven by a stepper motor or a servo motor as an electrically controllable optical switch.

[0061] The controller (which can be integrated into an industrial computer or a PLC) is configured to receive the thickness parameter of the material to be cut from the thickness measurement sensor or the human-machine interface, and compare the parameter with the built-in predetermined threshold (in this embodiment, the threshold is preferably set to 10 μm). Based on the comparison result, the controller issues a switching instruction to the longitudinal and transverse cutting optical system: if the thickness > 10 μm, the drive motor moves the mirror to the first working position corresponding to the Bessel optical system 2, so that the light beam enters the Bessel optical system 2; if the thickness ≤ 10 μm, the drive is to the second working position corresponding to the time compression and spatial dispersion system 3, so that the light beam enters the time compression and spatial dispersion system 3.

[0062] Please refer to Figure 2 , the Bessel optical system 2 includes a cone lens 21 and a lens group 22 arranged in sequence along the optical path, and as a preferred embodiment, the lens group 22 is a 4f lens system composed of a first focusing mirror and a second focusing mirror. The femtosecond laser beam first passes through the cone lens 21, which has a unique conical structure to convert the incident Gaussian beam into a Bessel beam with a central bright spot and non-diffraction characteristics. Subsequently, the Bessel beam is spatially filtered and Fourier transformed by the 4f lens system composed of the first focusing mirror and the second focusing mirror, thereby precisely regulating the focal depth length and spot diameter of the Bessel beam, and finally focusing the long focal depth Bessel beam inside the material to form a uniform modified layer. By moving the sample stage, the non-diffraction characteristics of the beam can be used to achieve high-quality one-time longitudinal cutting of thick materials, effectively avoiding the problems of cutting taper and top burning.

[0063] Please refer to Figure 3 , the time compression and spatial dispersion system 3 is used to realize high-precision space-time focusing cutting. The system includes a laser beam expander 31, a reflection grating 32, a first mirror 33 and a second mirror 34 arranged perpendicular to each other and installed on a high-precision axial displacement platform 35, a third mirror 36, and a laser focusing system 37 arranged in sequence along the optical path.

[0064] The working principle of the time compression and spatial dispersion system 3 is as follows: the femtosecond laser beam is first expanded by a laser beam expander 31, and then is incident to a reflective grating 32. The reflective grating 32 produces different diffraction angles for different wavelengths of light, realizing spatial dispersion and obtaining a first spectrum separated in space. The first spectrum is reflected by a mirror pair composed of a first mirror 33 and a second mirror 34, returns to the reflective grating 32 along the original path, and is diffracted and collimated for the second time, forming a parallel spectrum in which different wavelength components propagate in parallel in space.

[0065] To realize the core effect of "spatiotemporal double focusing", the system introduces an active dispersion compensation mechanism. By precisely driving a high-precision axial displacement platform 35, the optical path difference between the mirror pair and the reflective grating 32 can be accurately adjusted. This optical path difference is used to introduce a dispersion amount opposite to the negative dispersion introduced by the laser focusing system 37, thereby accurately compensating the temporal dispersion and re-synchronizing the laser components of different wavelengths in time.

[0066] Subsequently, the parallel spectrum after dispersion compensation is turned by a third mirror 36, enters the laser focusing system 37 (such as a high numerical aperture objective lens), and is spatiotemporally focused at a pre-set depth in the material. At this focal point, the laser pulse achieves extremely high energy density in space and time, realizes transverse cutting of the material through nonlinear absorption effect, and hardly damages the material outside the focal point, thereby reducing the heat affected zone to sub-micron level and obtaining a precise cutting effect with smooth edges and no micro-cracks.

[0067] The "spatiotemporal double focusing" in the present application refers to, in the time compression and spatial dispersion system 3, spatial dispersion by the reflective grating 32, reflection of the beam back to the grating for collimation by the mirror pair composed of the first mirror 33 and the second mirror 34, and adjustment of the optical path by the axial displacement platform 35 to compensate for the temporal dispersion (i.e. group velocity dispersion) generated in the transmission and focusing process of the laser pulse, so that the different wavelength components of the laser pulse can reach the focal point in the material at the same time. This enables the laser energy to be highly concentrated in both spatial and temporal dimensions, thereby forming extremely high peak power density at the focal point and realizing efficient and precise cutting.

[0068] Please refer to Figure 4 , based on the above adaptive cutting system, an adaptive cutting method based on femtosecond laser, comprising the following steps: first, the controller receives the thickness parameter (automatically acquired or manually input), and compares and judges with the preset threshold (such as 10 μm); then, the controller drives the longitudinal and transverse cutting optical system to switch the light path according to the judgment result: if it is a thick material, the Bessel optical system 2 is enabled for long focal depth longitudinal cutting; if it is a thin material, the time compression and spatial dispersion system 3 is enabled for spatiotemporal double focusing transverse cutting.

[0069] Second embodiment:

[0070] This embodiment is based on the first embodiment, by introducing cutting quality real-time monitoring module and dynamic closed-loop control logic, realized from "based on the preset parameters of static switching" to "based on the real-time processing quality of dynamic optimization" across, aims to solve the cutting process due to material or process fluctuations caused by microscopic quality defects.

[0071] The system architecture of this embodiment is shown in Figure 5 Based on all components of the first embodiment, a cutting quality real-time monitoring module is added to the controller signal connection.

[0072] As a preferred embodiment, the cutting quality real-time monitoring module is a spectral monitoring unit. Its specific integration method is: through a beam splitter, it is seamlessly integrated into the laser transmission path from femtosecond laser 1 to the material to be cut, so that its acquisition probe can accurately aim at the laser processing point, and be used for real-time acquisition of laser-induced plasma spectrum signals generated during processing.

[0073] The control logic of this embodiment constitutes a complete "perception-decision-execution" closed loop. The specific steps are as follows:

[0074] (1) Initial mode selection

[0075] The system first strictly follows the logic in the first embodiment: the controller compares the obtained thickness parameter with the predetermined threshold (such as 10 μm) and selects the Bessel cutting mode or the spatiotemporal focusing cutting mode as the "main cutting mode" for this cutting task. This mode will be responsible for completing most of the cutting tasks.

[0076] (2) Real-time quality feedback and dynamic decision

[0077] During the cutting process of the "main cutting mode", the cutting quality real-time monitoring module continuously transmits the acquired plasma spectrum signals to the controller.

[0078] The controller has pre-stored "quality threshold" corresponding to the "insufficient cutting depth" defect, which is specifically a preset intensity value representing the continuous background spectrum intensity of the material not completely vaporized. This threshold can be calibrated through early process experiments. The calibration method includes: cutting the sample material that is completely cut through under the standard process parameters, acquiring the continuous background intensity value of its plasma spectrum, and setting the intensity value with a certain safety factor as the threshold.

[0079] If the real-time monitoring signal is better than or equal to the quality threshold, the controller maintains the current main cutting mode.

[0080] If the real-time monitoring signal is worse than the quality threshold (i.e. the continuous background spectrum intensity is lower than the preset value), the controller determines that there is a risk of "insufficient cutting depth" at present, and immediately triggers the dynamic switching mechanism.

[0081] (3) Execution of the composite cutting process

[0082] After the dynamic switching mechanism is triggered, the controller executes the following composite machining process:

[0083] Instantaneous switching: the controller immediately issues an instruction to the longitudinal and transverse cutting optical system to temporarily switch the laser beam from the current "main cutting mode" to the "finishing cutting mode".

[0084] Finishing machining: the "finishing cutting mode" utilizes its unique machining advantages to perform compensation machining on the "insufficient cutting depth" area. As a key optimization, the "finishing cutting mode" and the "main cutting mode" are provided by the Bessel optical system 2 and the time compression and spatial dispersion system 3, respectively. For example:

[0085] Scenario A: when the main cutting mode is Bessel cutting (used for thick materials), if it is monitored that the bottom is not cut through, switch to the time-space focusing cutting mode. The latter utilizes its extremely high peak power density to "clean up" the cutting bottom, ensuring that it is cut through.

[0086] Scenario B: when the main cutting mode is time-space focusing cutting (used for thin materials), if it is monitored that a certain area needs more removal, the Bessel cutting mode can be temporarily switched to perform rapid etching.

[0087] (4) Judgment of finishing and mode recovery

[0088] To ensure the integrity and feasibility of the process, the present application specifically provides specific criteria for judging "finishing". The following are all feasible embodiments:

[0089] Criterion one (based on time control): a fixed duration (e.g. 5-20 milliseconds) is preset for finishing machining. This duration is determined through process experiments and is sufficient to repair such defects. When the time is up, the controller determines that the finishing is complete.

[0090] Criterion two (based on signal feedback control): during the finishing process, the plasma spectrum signal is continuously monitored. When the signal (such as the continuous background spectrum intensity) is restored to be better than the quality threshold, the controller determines that the defect has been eliminated and the finishing is complete.

[0091] Criterion three (based on position control): in combination with the coordinate information of the motion system, a finishing path is preset for the recognized defect area. When the laser machining head completes the scanning of the path, it is determined that the finishing is complete.

[0092] The above judgment criteria can be used alone or in combination according to process requirements. When used in combination, a priority can be set, such as determining completion when any condition is met, or requiring multiple conditions to be met simultaneously.

[0093] Once the "finishing is completed" is determined, the controller immediately instructs the longitudinal and transverse cutting optical system to switch back to the original "main cutting mode" to continue the subsequent cutting task.

[0094] In the present application, the main cutting mode refers to the cutting mode selected by the controller according to the comparison result of the thickness parameter of the material to be cut with the predetermined threshold value (such as 10 μm). That is: when the thickness is greater than the threshold value, the main cutting mode is the Bessel cutting mode; when the thickness is less than or equal to the threshold value, the main cutting mode is the spatiotemporal focusing cutting mode. This mode is responsible for completing most of the cutting tasks. The finishing cutting mode refers to another cutting mode different from the main cutting mode, which is used to compensate for specific processing defects diagnosed in real time during the main cutting process. For example: when the main cutting mode is the Bessel mode, the finishing cutting mode is the spatiotemporal focusing mode, which uses its high precision and high peak power characteristics to solve the problem of insufficient cutting depth; when the main cutting mode is the spatiotemporal focusing mode, the finishing cutting mode is the Bessel mode, which uses its long focal depth and large volume removal characteristics to solve the problem of excessive heat-affected zone or the need for rapid etching. Taking the cutting of a 15 μm thick sapphire wafer as an example, the system first uses the Bessel mode as the main cutting mode. When the continuous background intensity of the plasma spectrum is lower than the threshold value (indicating that the bottom is not cut through), the controller switches to the spatiotemporal focusing mode for finishing. During the finishing process, the controller continuously monitors the spectrum signal, and once the intensity returns to above the threshold value, it is determined that the finishing is completed, and the Bessel mode is automatically switched back to continue cutting.

[0095] Correspondingly, please refer to Figure 6 The femtosecond laser-based adaptive cutting method in the present embodiment further includes the following steps during the cutting process:

[0096] Based on the real-time acquired processing quality monitoring signal, the Bessel cutting mode and the spatiotemporal focusing cutting mode are dynamically decided and switched between to compensate for the processing defects online.

[0097] In combination with the current actual needs, the above-mentioned embodiments adopted by the present application are not limited thereto, and various changes made within the knowledge range of those skilled in the art without departing from the concept of the present application still fall within the protection scope of the present application.

Claims

1. A femtosecond laser-based adaptive cutting method, characterized by, The method comprises the following steps: acquiring a thickness parameter of the material to be cut and comparing the thickness parameter with a predetermined threshold value; if the thickness parameter is greater than the predetermined threshold value, controlling a longitudinal and transverse cutting optical system to direct a femtosecond laser beam to a Bessel optical system (2); the Bessel optical system (2) converts the laser beam into a Bessel beam by using a conical lens (21) and focuses the Bessel beam into the material for longitudinal cutting by using a lens group (22); if the thickness parameter is less than or equal to the predetermined threshold value, controlling the longitudinal and transverse cutting optical system to direct the femtosecond laser beam to a time compression and spatial dispersion system (3); the time compression and spatial dispersion system (3) spatially disperses the laser beam by using a reflective grating (32) and reflects the dispersed laser beam back to the reflective grating (32) by using a mirror pair composed of a first mirror (33) and a second mirror (34) to collimate the laser beam, and finally time and spatially focuses the collimated parallel light spectrum into the material for transverse cutting; the predetermined threshold value is 10 μm; the lens group (22) is a 4f lens system composed of a first focusing mirror and a second focusing mirror, which is used to adjust the focal depth and spot diameter of the Bessel beam; in the time compression and spatial dispersion system (3), the collimated parallel light spectrum is time dispersion compensated to make different wavelength components re-synchronized in time; in the time compression and spatial dispersion system (3), the optical path between the first mirror (33) and the second mirror (34) and the reflective grating (32) is adjusted by driving an axis displacement platform (35) to realize the time dispersion compensation; the time dispersion compensation is used to realize time and spatial focusing of the laser pulse when focusing.

2. The method of claim 1, wherein the femtosecond laser-based adaptive cutting method is characterized by, In the cutting process, the following steps are further included: real-time acquisition of a monitoring signal used to reflect the cutting quality; comparison of the monitoring signal with a preset quality threshold value; if the monitoring signal is worse than the quality threshold value, controlling the longitudinal and transverse cutting optical system to dynamically switch the cutting mode.

3. The method of claim 2, wherein the femtosecond laser-based adaptive cutting method is characterized by, the monitoring signal is a laser-induced plasma spectrum signal; the monitoring signal being worse than the quality threshold value means that the continuous background spectrum intensity representing incomplete vaporization of the material is lower than a preset intensity threshold value; the dynamic switching of the cutting mode means that the current main cutting mode is temporarily switched to another fine cutting mode, and then switched back to the main cutting mode after the fine cutting is completed; the main cutting mode and the fine cutting mode correspond to two different cutting modes provided by the Bessel optical system (2) and the time compression and spatial dispersion system (3) respectively.

4. A femtosecond laser based adaptive cutting system for implementing the adaptive cutting method of any one of claims 1 to 3, characterized in that, The method comprises: a femtosecond laser (1); a longitudinal and transverse cutting optical system, the light path input end of which is connected to the femtosecond laser (1), and the light path output end of which is switchably connected to a Bessel optical system (2) or a time compression and spatial dispersion system (3); a Bessel optical system (2) comprising a conical lens (21) and a lens group (22) arranged in sequence along the light path; The time compression and space dispersion system (3) comprises a laser beam expander (31), a reflection grating (32), and a first reflection mirror (33) and a second reflection mirror (34) arranged perpendicularly to each other in sequence along an optical path. The controller is in signal connection with the longitudinal and transverse cutting optical system and is configured to receive the thickness parameter and send a switching instruction to the longitudinal and transverse cutting optical system according to a comparison result of the thickness parameter and a predetermined threshold.

5. The femtosecond laser-based adaptive cutting system of claim 4, wherein, The longitudinal and transverse cutting optical system is an electrically controllable optical switch or optical path switcher, and the lens group (22) is a 4f lens system.

6. The femtosecond laser based adaptive cutting system of claim 4, wherein, The time compression and space dispersion system (3) further comprises an axial displacement platform (35), a laser focusing system (37), and a third reflection mirror (36). The first reflection mirror (33) and the second reflection mirror (34) are installed on the axial displacement platform (35). The third reflection mirror (36) is used to reflect the parallel light spectrum emitted from the reflection grating (32) to the laser focusing system (37). The adaptive cutting system further comprises a thickness measurement sensor for automatically obtaining the thickness parameter of the material to be cut.

7. The femtosecond laser based adaptive cutting system of claim 4, wherein, The adaptive cutting system further comprises a cutting quality real-time monitoring module in signal connection with the controller. The controller is further configured to: receive a monitoring signal reflecting the cutting quality from the cutting quality real-time monitoring module; compare the monitoring signal with a preset quality threshold; if the monitoring signal is worse than the quality threshold, generate a dynamic switching instruction and send it to the longitudinal and transverse cutting optical system.

8. The femtosecond laser-based adaptive cutting system of claim 7, wherein, The cutting quality real-time monitoring module is a spectrum monitoring unit integrated in a laser transmission optical path from the femtosecond laser (1) to the material to be cut through a beam splitter, for collecting plasma spectrum signals at a machining point.

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