Device for processing pole piece by ultrafast laser

Abstract

The utility model relates to an ultrafast laser processing pole piece device, which is characterized in that an ultrafast laser, a light box, a reflecting mirror I, a one-dimensional motion unit and an X-axis motion unit are arranged on a rack, a multi-focus diffraction optical element is arranged on the one-dimensional motion unit, a bottom plate is connected onto the X-axis motion unit, a reflecting mirror II and a Z-axis motion module are arranged on the bottom plate, and the Z-axis motion module is connected onto the X-axis motion unit. A third reflecting mirror and a galvanometer and field lens unit are installed on the Z-axis movement module, a light box, a first reflecting mirror, a multi-focus diffraction optical element, a second reflecting mirror, the third reflecting mirror and the galvanometer and field lens unit are sequentially arranged on an output light path of the ultrafast laser, and a Y-axis movement unit is arranged below the galvanometer and field lens unit. And an adsorption platform for adsorbing and loading the pole piece is arranged on the Y-axis movement unit. A pole piece is drilled or cut, a transmission light path obtains multiple focuses through a one-dimensional beam splitting diffraction optical element, and the hole is drilled in the pole piece to improve the inlet and outlet speed of lithium ions; when the pole piece is cut, the one-dimensional beam splitting diffraction optical element is switched to the outside of the transmission light path, and the light beam behind the field lens is a single focus.

Description

Technical Field

[0001] The utility model relates to a device for ultrafast laser processing of pole pieces, belonging to the technical field of laser processing. Background Art

[0002] The open document (Paving the way for industrial ultrafast laser structuring of lithium-ion battery electrodes by increasing the scanning accuracy) discloses a method of drilling holes in graphite negative electrodes using a high-speed rotating mirror, with a rotating mirror speed of up to 2 km / s, control accuracy upgraded from 10 ns to 0.5 ps, and repeatability improved from 20 μm to 1 nm. The rotating mirror is suitable for processing straight line patterns in one direction, and the speed difference with the galvanometer is large, making it difficult to cooperate with it to cut curved patterns.

[0003] Patent publication number CN 114603253 A discloses a multi-galvanometer laser film-making method and system for positive electrode pieces, which uses a high-precision 20-bit resolution galvanometer and a 250W-1000W high-power laser; the cost is high. Patent publication number CN114603253 A discloses a multi-galvanometer laser film-making method and system for positive electrode pieces, the laser is 2MHz to 10MHz, the frequency is high, and the point spacing is 35 microns at a maximum speed of 70,000mm / s, which cannot meet the hole spacing requirements of more than 100 microns; the single pulse energy of a 250W to 1000W laser at 2MHz does not exceed 0.5mJ, which is difficult to meet the beam splitting requirements.

[0004] It is difficult to flexibly adjust the width, direction, depth and spacing of the processing area, and it is difficult to ensure the uniformity of spacing, diameter, depth and channel structure. It is difficult to be compatible with the production line. Too many pulses may accumulate at the processing starting point, end point and corners, breaking down the current collector to form burrs, piercing the diaphragm and causing battery short circuit. The speed difference between the rotating mirror and the galvanometer is large, making it difficult to coordinate them to cut curved patterns. The high-precision resolution galvanometer is expensive, and the single laser pulse energy does not exceed 0.5mJ, which is difficult to meet the beam splitting requirements. Utility Model Content

[0005] The purpose of the utility model is to overcome the shortcomings of the prior art and provide a device for ultrafast laser processing of pole pieces, which can drill holes or cut pole pieces to achieve high-speed, large-format, roll-to-roll or roll-to-piece processing of pole pieces.

[0006] The purpose of the utility model is achieved through the following technical solutions:

[0007] The device for ultrafast laser processing of pole pieces is characterized by: an ultrafast laser, a light box, a first reflector, a one-dimensional motion unit and an X-axis motion unit are installed on a frame, a multi-focus diffractive optical element is installed on the one-dimensional motion unit, a bottom plate is connected to the X-axis motion unit, a second reflector and a Z-axis motion module are installed on the bottom plate, a third reflector and a galvanometer field lens unit are installed on the Z-axis motion module, the light box, the first reflector, the multi-focus diffractive optical element, the second reflector, the third reflector and the galvanometer field lens unit are arranged in sequence on the output optical path of the ultrafast laser, a Y-axis motion unit is arranged below the galvanometer field lens unit, and an adsorption platform for adsorbing and loading the pole piece is provided on the Y-axis motion unit;

[0008] A dust collecting device is arranged beside the adsorption platform, an aperture is installed between the dust collecting device and the pole piece, and the adsorption platform and the dust collecting device are connected to a vacuum system.

[0009] Furthermore, in the above-mentioned ultrafast laser processing pole piece device, the frame is a marble frame fixed on a marble base.

[0010] Furthermore, in the above-mentioned ultrafast laser processing pole piece device, the light box includes a reflector four and a beam expander arranged in sequence along the light path.

[0011] Furthermore, in the above-mentioned ultrafast laser processing pole piece device, the ultrafast laser is an ultrafast laser with a pulse width of 290fs to 15ps, a power of 100W to 600W, and a frequency of 50kHz to 40MHz.

[0012] Furthermore, in the above-mentioned ultrafast laser processing pole piece device, the multi-focal diffractive optical element is a multi-focal diffractive optical element with a multi-focal separation angle ≤ 0.230° and a focal number not exceeding 300, and the multi-focal diffractive optical element is mounted on a one-dimensional motion unit.

[0013] Furthermore, in the above-mentioned ultrafast laser processing pole piece device, an aperture is installed between the galvanometer field lens unit and the pole piece, and two apertures are arranged along the coil feeding direction.

[0014] Furthermore, in the above-mentioned ultrafast laser processing pole piece device, a camera module for focusing is installed on the bottom plate.

[0015] Compared with the prior art, the present invention has significant advantages and beneficial effects, which are specifically embodied in the following aspects:

[0016] The utility model uses ultrafast laser to drill or cut the pole piece, and the transmission light path passes through a one-dimensional beam splitting diffraction optical element to obtain multiple focal points. Drilling holes on the pole piece increases the speed of lithium ion entry and exit, and increases the battery capacity during rapid charging and discharging. The process after drilling is cutting and laminating, which has the function of cutting the pole piece. When cutting the pole piece, the one-dimensional beam splitting diffraction optical element is switched to the outside of the transmission light path, and the light beam behind the field mirror is a single focal point. With the reel loading, a multi-head galvanometer is used, and through intermittent processing, aluminum foil, ceramics, and pole piece areas are cut according to the processing drawings, or holes are drilled in the pole piece in the designated area. After the processing is completed, the reel unwinds the material or the platform shaft unwinds the sheet material. High-speed, large-format, roll-to-roll or roll-to-sheet processing of pole pieces is achieved, and it has the advantages of strong versatility, high processing efficiency, no need for flattening, and a wide range of applicable pole pieces.

[0017] Other features and advantages of the utility model will be described in the following description, and partly become apparent from the description, or understood by implementing the specific implementation of the utility model. The purpose and other advantages of the utility model can be achieved and obtained by the structures specifically pointed out in the written description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 : A schematic diagram of the front view of the device of the utility model;

[0020] Figure 2 : A side view schematic diagram of the device of the utility model;

[0021] Figure 3 : Schematic diagram of splicing and processing pole pieces. DETAILED DESCRIPTION

[0022] The technical scheme in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, rather than all the embodiments. The components of the embodiment of the utility model generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiment of the utility model provided in the drawings is not intended to limit the scope of the utility model claimed for protection, but merely represents the selected embodiment of the utility model. Based on the embodiment of the utility model, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the utility model.

[0023] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the utility model, directional terms and order terms are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0024] like Figures 1 to 3 As shown, an apparatus for ultrafast laser processing of pole pieces, an ultrafast laser 10, a light box 1, a reflector 20, a one-dimensional motion unit and an X-axis motion unit 16 are installed on a frame 2, the frame 2 is a marble frame, fixed on a marble base 15, the light box 1 comprises a reflector 4 and a beam expander arranged in sequence along the light path, a multi-focal diffractive optical element 5 is installed on the one-dimensional motion unit, a base plate 19 is connected to the X-axis motion unit 16, a reflector 21 and a Z-axis motion module 3 are installed on the base plate 19, a reflector 3 4 and a galvanometer field lens unit 12 are installed on the Z-axis motion module 3, the light box 1, the reflector 20, the multi-focal diffractive optical element 5, the reflector 21, the reflector 3 4 and the galvanometer field lens unit 12 are arranged in sequence on the output light path of the ultrafast laser 10, a Y-axis motion unit 7 is arranged below the galvanometer field lens unit 12, and an adsorption platform 14 for adsorbing and loading the pole piece is provided on the Y-axis motion unit 7. A camera module 6 for focusing is mounted on the bottom plate 19 to focus on pole pieces of different thicknesses.

[0025] A dust collector 13 is provided next to the adsorption platform 14, and an aperture 22 is installed between the dust collector 13 and the pole piece. The adsorption platform 14 and the dust collector 13 are connected to the vacuum system through a pipeline tee 11. The airflow of the dust collector is laminar flow rather than turbulent flow. The laminar flow has a fast flow rate, and the turbulent flow is difficult to unidirectionally adsorb dust generated by drilling or cutting; the airflow velocity in the dust collector pipeline is greater than 1m / s, and preferably the flow velocity in the pipeline is greater than or equal to 23m / s during cutting, and the dust collector 13 covers the processing area.

[0026] The equipment cooperates with reel loading, reel unloading or platform for sheet unloading.

[0027] A hole is drilled on the pole piece, and an aperture is installed between the galvanometer field lens unit 12 and the pole piece to prevent the collector from being punctured and generating burrs at the starting point, end point or corner of the edge of the drilling area. The two apertures are arranged along the feeding direction of the coil material and do not block the vertical direction of the feeding direction during cutting.

[0028] The ultrafast laser 10 is an ultrafast laser with a pulse width of 290fs to 15ps, a power of 100W to 600W, and a frequency of 50kHz to 40MHz. Preferably, the power is 200W to 500W, the slab amplifier has a large single-pass gain, and can reach 500W through a single-pass or multi-pass amplifier, and has multiple sub-pulse functions; the disk amplifier has a low single-pass gain coefficient, and can reach 780W through multiple amplifications in the regeneration cavity, and the single pulse energy reaches 2.6mJ, but there are no multiple sub-pulses; preferably, the frequency is 100kHz to 10MHz; the maximum single pulse energy of the ultrafast laser reaches the mJ level, and preferably the maximum single pulse energy is 3mJ. Drilling requires a small crater, maintaining or approaching the flatness before drilling to avoid spikes piercing the diaphragm. Ultrashort pulse laser ablation processing, small crater, no need for leveling operation.

[0029] An ultrafast laser and a galvanometer are used to drill or cut a hole on the pole piece. A hole is drilled on the pole piece, and the transmission light path passes through a one-dimensional beam splitting multi-focus diffractive optical element 5 to obtain a multi-focus. The galvanometer controls the card position using 16 bits or more. A single focus is used for cutting the pole piece. The one-dimensional beam splitting multi-focus diffractive optical element 5 is switched through a one-dimensional motion unit. The one-dimensional beam splitting multi-focus diffractive optical element 5 can be switched in the transmission light path or externally. The multi-focus diffractive optical element 5 is a multi-focus diffractive optical element with a multi-focus separation angle ≤ 0.230° and a focus number not exceeding 300. The number of focuses should be greater than or equal to 1, and the preferred number of focuses is more than 10 and less than 80.

[0030] The entire device is supported by a foot adjustment mechanism 8, which is used to adjust the height and levelness.

[0031] The electrode piece 28 includes a positive electrode or a negative electrode piece. The positive electrode piece includes ternary lithium or lithium iron phosphate, and the negative electrode piece includes natural graphite, and a mixture of natural graphite and mesophase carbon microbeads, modified artificial graphite, and silicon-carbon composite negative electrode material.

[0032] The ultrafast laser 10 emits an ultrafast pulse laser which passes through the light box 1, then passes through the reflector 1 20, passes through the multi-focus diffraction optical element 5, and then passes through the reflector 2 21 and the reflector 3 4 to enter the galvanometer field lens unit 12, and is focused on the pole piece on the adsorption platform 14; the Z-axis motion module 3 can drive the reflector 3 4 and the galvanometer field lens unit 12 to move up and down, and the galvanometer field lens unit 12 moves up and down to adjust the laser focus to the pole piece surface; the camera module 6 is used to find the focus for pole pieces of different thicknesses; the X-axis motion unit 16 drives the reflector 2 21, the reflector 3 4 and the galvanometer field lens unit 12 to move, and adjusts the machining center of the pole piece along the X-axis.

[0033] The pole piece is carried on the adsorption platform 14, and the Y-axis motion unit 7 drives the adsorption platform 14 to move. After reaching the processing position, the adsorption platform 14 is stationary during processing, and the galvanometer field lens unit 12 moves along the processing track 1 26 or the processing track 2 29, and controls the switch of the ultrafast laser 10 at the processing starting point and turns off the ultrafast laser 10 at the processing end point; after processing an area, the Y-axis motion unit 7 pulls the pole piece, and the moving distance is the length of the processing area plus the pattern spacing; the roll-to-roll or roll-to-sheet loading and unloading device uses PLC to adjust tension, correct deviation, rotate, adjust speed, etc., and interacts with the host. The host operation is the display 18, which controls loading, ultrafast laser 10, galvanometer field lens unit 12, Z-axis motion module 3, X-axis motion unit 16, Y-axis motion unit 7, etc.

[0034] The pole piece 28 moves along the Y direction, and the processing tracks 1 26 or 29 of the two scanning areas are spliced ​​into the processing area of ​​the slurry area 25. The pole piece 28 is composed of the aluminum foil area, the ceramic area 24 and the slurry area 25; the drilling processing track 1 26 and the processing track 2 29 are composed of a bow-shaped closed pattern, and there is only one starting point and end point along the arrow 23, which reduces the delay of the starting point and end point in the middle area. The corner 27 has a long residence time due to deceleration and acceleration, which makes it easy to penetrate the aluminum foil and the hole spacing becomes smaller; the laser is blocked by the aperture 22 to damage the aluminum foil, and the aperture 22 is located at both ends of the processing track 1 26 and the processing track 2 29 in the Y direction; for the square hole 31, the line spacing in the processing track 1 26 is equal to the hole spacing; for the diamond hole 32, the line spacing in the processing track 2 29 is equal to the hole spacing multiplied by The drilling processing trajectory 1 26 and the processing trajectory 2 29 are multi-segment lines, but when the galvanometer field lens unit 12 moves at high speed along the Y direction, the laser pulse is irradiated at discrete position points to form equally spaced holes rather than line segments. The spacing between holes 30, square holes 31, and diamond holes 32 is 200 μm and the depth is 41 μm. The processing method of 4, 6, 8 and other multiple splicing areas is similar, and the slurry area is spliced ​​along the Y direction.

[0035] The dust collecting device 13 covers the processing area, and the airflow of the dust collecting device is laminar, which unidirectionally absorbs the dust generated by drilling or cutting, and the flow rate is greater than or equal to 23m / s; the aperture 22 installed between the dust collecting device 13 and the pole piece is used to prevent the aluminum foil from being perforated and the hole spacing from becoming smaller.

[0036] In order to take into account the speed, format and hole spacing, a focal length of more than 100mm is used, the hole spacing is 200 microns, and considering the interval processing, the multi-focus separation angle is ≤0.230°. In order to ensure that the power of each beam is sufficient for processing, the number of focal points does not exceed 300, and the preferred number of focal points does not exceed 80; in order to make full use of the laser power, the number of focal points is greater than or equal to 1, and the preferred number of focal points is more than 10. The diffractive optical element adopts a high-efficiency model.

[0037] Example 1

[0038] An ultrafast laser is used to drill holes on the lithium cobalt oxide pole piece. The 500W laser transmits the galvanometer with a pulse width of 10ps. The square hole spacing is 200μm. A high-efficiency one-dimensional beam splitting diffraction optical element standard is used. The beam splitting angle is 0.028°, the focal length of the field lens is 409mm, and the beam is divided into 15 beams after the galvanometer. The processing frequency is 200kHz and the speed is 40m / s. The galvanometer processing format is 25mm, and the galvanometer control card position is 16. The processing depth is 30μm. If only a 25mm area is processed, the corresponding winding speed is 5m / minute. If a 120mm wide pole piece is processed, a certain gap is left between the processing areas to avoid overlapping and drilling through the current collector. Four sets of lasers are used in conjunction with galvanometers to process a 25×4=100mm area, and the corresponding winding speed is 5m / minute.

[0039] Example 2

[0040] Ultrashort pulse laser drilling on graphite pole piece, single laser dual galvanometer processing, laser power 300W, pulse width 800fs. The diamond hole spacing is 173 microns, using high-efficiency one-dimensional beam splitting diffraction optical element standard, the beam splitting angle is 0.060°, the focal length of the two field mirrors is 330mm, and the beam is divided into 13 beams after the galvanometer. The processing frequency is 100kHz, the processing speed is 20m / s, the pole piece width is 120mm, the single galvanometer processing format is 50mm, the drilling depth is 40μm, and the corresponding coil speed is 10m / min.

[0041] Example 3

[0042] A 300W ultrafast laser is used to cut lithium iron phosphate pole pieces, with a pulse width of 300fs and a frequency of 4MHz. The laser processes a 180-micron thick pole piece, of which the ceramic thickness is 120μm, and the equivalent processing speed is 1000mm / s. For a 300mm long pole piece, the laser cutting time plus the material pulling time is about 0.43s, the pole piece width is 120mm, and the processing efficiency is 16.7m / minute. For a 600mm long pole piece, a dual laser is used to achieve a processing efficiency of 16.7m / minute.

[0043] Example 4

[0044] A 200W ultrafast laser is used to cut lithium iron phosphate pole pieces, with a pulse width of 14ps and a frequency of 5MHz. The laser processes a 180-micron thick pole piece, of which the ceramic thickness is 60 microns, with an equivalent processing speed of 1500mm / s. For a 300mm long pole piece, the laser cutting time plus the material pulling time is about 0.32s, the pole piece width is 120mm, and the processing efficiency is 22.5m / minute. For a 600mm long pole piece, a dual laser is used to achieve a processing efficiency of 22.5m / minute.

[0045] Laser drilling is used for pole piece materials such as graphite and lithium cobalt oxide. The structure of lithium cobalt oxide includes monoclinic, hexagonal, layered or spinel structures, and lithium ions can move quickly between layers or in larger channels; lithium iron phosphate has an orthorhombic olivine structure, and the lithium ion diffusion channel is a one-dimensional channel; graphite has a layered structure, and lithium ions can move quickly between layers. After laser processing, the structure or composition of the active material deposited in the heat-affected zone changes, affecting the lithium ions from entering the pole piece from the front, so the smaller the heat-affected zone, the better. When charging, lithium ions move from lithium cobalt oxide or lithium iron phosphate to graphite, and are embedded in the ring composed of C atoms through the electrolyte.

[0046] The laser drilling process avoids shock waves and compacts the area around the processing area to reduce the distance between atoms and hinder the entry of lithium ions. The laser drilling should be as deep as possible in the graphite layer, and it is necessary to avoid damaging the aluminum foil current collector to prevent lithium ions from gathering on the aluminum foil and precipitating lithium. The holes should be as dense as possible to improve the efficiency of lithium ion migration. Since the diffusion coefficient of lithium ions in graphite is 10 -13 -10 -6 cm 2 / s, the diffusion coefficient of lithium nickel manganese oxide is 10 -8 cm 2 / s. The reference (Increasing the Discharge Rate Capability of Lithium-Ion Cells with Laser-Structured Graphite Anodes: Modeling and Simulation) summarizes the diffusion parameters in the positive and negative electrodes and the electrolyte. The diffusion coefficient of the graphite aluminum foil negative electrode is 10-14 cm 2 / s, positive electrode diffusion coefficient 1.8×10 -13 cm 2 / s, the diffusion coefficient of the electrolyte with a concentration of 3 mmol at room temperature is 5.8×10 -11 cm 2 / s, which is equivalent to 5800 times the diffusion coefficient in graphite. The radius of lithium ions is only 0.068nm, so the micron-scale pores are enough for lithium ions to pass through the electrolyte. The diffusion time is inversely proportional to the diffusion coefficient. When lithium ions are charged, most of the movement time of lithium ions is in graphite.

[0047] In summary, the utility model uses ultrafast laser to drill or cut the pole piece, and the transmission light path passes through a one-dimensional beam splitting diffractive optical element to obtain multiple focal points. Drilling holes on the pole piece increases the speed of lithium ion entry and exit, and increases the battery capacity during rapid charging and discharging. The process after drilling is cutting and laminating, which has the function of cutting the pole piece. When cutting the pole piece, the one-dimensional beam splitting diffractive optical element is switched to the outside of the transmission light path, and the light beam after the field lens is a single focal point. With the reel loading, a multi-head galvanometer is used, and through intermittent processing, aluminum foil, ceramics, and pole piece areas are cut according to the processing drawings, or holes are drilled in the pole piece in the designated area. After the processing is completed, the reel unwinds the material or the platform shaft unwinds the sheet material. High-speed, large-format, roll-to-roll or roll-to-sheet processing of pole pieces is achieved, which has the advantages of strong versatility, fast processing efficiency, no need for flattening, and a wide range of applicable pole pieces.

[0048] The above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. For those skilled in the art, the utility model may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0049] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention.

[0050] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

Claims

1. An apparatus for ultrafast laser processing of pole pieces, characterized in that: An ultrafast laser (10), a light box (1), a reflector 1 (20), a one-dimensional motion unit and an X-axis motion unit (16) are mounted on the frame (2); a multi-focal diffractive optical element (5) is mounted on the one-dimensional motion unit; a base plate (19) is connected to the X-axis motion unit (16); a reflector 2 (21) and a Z-axis motion module (3) are mounted on the base plate (19); a reflector 3 (4) and a galvanometer field lens unit (12) are mounted on the Z-axis motion module (3); the light box (1), the reflector 1 (20), the multi-focal diffractive optical element (5), the reflector 2 (21), the reflector 3 (4) and the galvanometer field lens unit (12) are arranged in sequence on the output light path of the ultrafast laser (10); a Y-axis motion unit (7) is arranged below the galvanometer field lens unit (12); and an adsorption platform (14) for adsorbing and loading pole pieces is provided on the Y-axis motion unit (7); A dust collecting device (13) is arranged beside the adsorption platform (14), an aperture (22) is installed between the dust collecting device (13) and the pole piece, and the adsorption platform (14) and the dust collecting device (13) are connected to a vacuum system.

2. The device for ultrafast laser processing of pole pieces according to claim 1, characterized in that: The frame (2) is a marble frame, which is fixed on a marble base (15).

3. The device for ultrafast laser processing of pole pieces according to claim 1, characterized in that: The light box (1) comprises a reflector 4 and a beam expander which are arranged in sequence along the light path.

4. The device for ultrafast laser processing of pole pieces according to claim 1, characterized in that: The ultrafast laser (10) has a pulse width of 290 fs to 15 ps, a power of 100 W to 600 W, and a frequency of 50 kHz to 40 MHz.

5. The device for ultrafast laser processing of pole pieces according to claim 1, characterized in that: The multifocal diffractive optical element (5) is a multifocal diffractive optical element with a multifocal separation angle of ≤0.230° and a focal number of no more than 300.

6. The device for ultrafast laser processing of pole pieces according to claim 1, characterized in that: An aperture is installed between the galvanometer field lens unit (12) and the pole piece, and the two apertures are arranged along the coil feeding direction.

7. The device for ultrafast laser processing of pole pieces according to claim 1, characterized in that: A camera module (6) for focusing is installed on the bottom plate (19).

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