Ultrafast laser processing system and processing method for diaphragm micro-holes

Abstract

The application provides an ultrafast laser processing system and method for diaphragm micro-holes, and belongs to the technical field of laser processing. The ultrafast laser processing system for diaphragm micro-holes comprises a displacement table, a laser assembly, an imaging monitoring assembly, a laser ranging assembly and a cleaning assembly. The metal sheet to be processed is arranged on the displacement table. The laser assembly comprises an ultrafast laser pulse generator for generating an ultrafast laser beam, and mirrors, a neutral density energy attenuation sheet, a variable magnification beam reducer and a focusing objective lens for adjusting the characteristic parameters of the ultrafast laser beam. The imaging monitoring assembly is suitable for monitoring the processing process. The laser ranging assembly is suitable for detecting the distance between the focal point of the ultrafast laser beam and the metal sheet to be processed. The cleaning assembly is suitable for removing the debris generated during the processing of the metal sheet to be processed. The processing method combines ring scanning or punching processing to process micro-holes with different diameters. The application can improve the processing precision, the roundness of the diaphragm micro-holes and the consistency of the import and export diameters, and improve the processing quality.

Description

Technical Field

[0001] The present invention relates to the field of laser processing technology, and in particular to an ultrafast laser processing system and a processing method for an aperture micro-hole. Background Art

[0002] The aperture is a key component for controlling light beams, electron beams or ion beams in semiconductor inspection equipment. It is composed of a metal sheet with a specific aperture. Its raw materials are mainly high-hardness and high-melting-point metal materials such as platinum and molybdenum. The aperture range is 1~2000μm. These micropores have high dimensional accuracy, roundness, and surface roughness quality. The aperture quality is closely related to the high precision, high resolution and low defect rate requirements of the semiconductor inspection process.

[0003] In the related technologies, metal aperture micro-hole processing methods include traditional mechanical processing, chemical etching, electric spark processing, etc. These methods have certain limitations in terms of processing accuracy, efficiency, material applicability, etc. In order to overcome this limitation, metal components are currently processed using ultrafast laser processing technology. Ultrafast laser processing technology has significant advantages in metal component processing due to its ultrashort pulse characteristics. "Ultrafast laser" refers to a pulsed laser with an output laser pulse width of picoseconds or less than picoseconds. Among them, femtosecond laser processing methods are more widely used. However, there are still some problems with the current femtosecond laser processing method:

[0004] 1. Heat-affected zone control: Femtosecond lasers may generate heat accumulation under high energy density or high repetition frequency conditions, causing microcracks or thermal damage on the material surface, reducing processing quality;

[0005] 2. Limitation of vertical structure processing accuracy: When achieving a specific depth of processing, the light field distribution of the femtosecond laser differs between the surface and the bottom surface. As the processing depth increases, the light field distribution of the femtosecond laser gradually deviates from the light field of the focal plane, increasing the roughness of the vertical structure sidewalls and making it difficult to achieve high-precision vertical structures.

[0006] 3. Balance between substrate removal and deposition: During femtosecond laser processing, there is a contradiction between the material removal rate and the formation of a recast layer. Although a longer laser processing time can increase the material removal rate, a recast layer will also form near the processing area, affecting the surface quality and reducing the processing accuracy. This is particularly significant for semiconductor testing.

[0007] The above problems will lead to problems such as poor roundness of micro-hole processing and inconsistent inlet and outlet apertures in the metal aperture. Summary of the Invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an ultrafast laser processing system and method for aperture micro-apertures, aiming to address problems such as poor roundness and uneven inlet and outlet diameters that occur when processing metal micro-apertures using ultrafast laser technology.

[0009] The present invention proposes an ultrafast laser processing system for an aperture microaperture, which includes a translation stage, a laser assembly, an imaging monitoring assembly, a laser ranging assembly, and a cleaning assembly. A metal sheet to be processed is arranged on the translation stage, and the translation stage is suitable for driving the metal sheet to be processed to move along a processing path. The laser assembly includes an ultrafast laser pulse generator, a reflector, a neutral density energy attenuation plate, a zoom lens, and a focusing objective lens. The ultrafast laser pulse generator is suitable for emitting an ultrafast laser beam. The reflector is suitable for adjusting the transmission path of the ultrafast laser beam so as to reflect the ultrafast laser beam to the metal sheet to be processed. The neutral density energy attenuation plate, the zoom lens, and the focusing objective lens are arranged in the transmission path of the ultrafast laser beam so as to adjust the characteristic parameters of the ultrafast laser beam. The imaging monitoring assembly is suitable for monitoring the processing process of the metal sheet to be processed. The laser ranging assembly is suitable for detecting the distance between the focus of the ultrafast laser beam and the metal sheet to be processed. The cleaning assembly is suitable for removing debris generated by the metal sheet to be processed during the processing.

[0010] In the ultrafast laser processing system for aperture microapertures disclosed herein, the laser assembly, in conjunction with a translation stage, enables mobile scanning processing, enabling flexible control of laser parameters during processing and ensuring consistent and repeatable aperture microaperture processing. Furthermore, the laser assembly improves processing efficiency by regulating the ultrafast laser beam. Furthermore, the incorporation of an imaging monitoring component, a laser ranging component, and a cleaning component improves the roundness of the aperture microaperture, controls the surface quality and heat-affected zone of the aperture microaperture, and ensures ultrafast laser beam processing quality.

[0011] According to some embodiments of the present invention, the imaging monitoring component includes an imaging light source, a semi-transparent and semi-reflective spectroscope, an imaging lens and a CCD camera; the imaging light source is suitable for emitting imaging light to the metal sheet to be processed, and the imaging light source and the focusing objective lens are arranged on the same optical axis, and the focusing objective lens is suitable for focusing the imaging light; the semi-transparent and semi-reflective spectroscope is suitable for the imaging light to pass through, and is suitable for reflecting the reflected light of the imaging light; the imaging lens is suitable for focusing the light reflected by the semi-transparent and semi-reflective spectroscope; the CCD camera is suitable for receiving the light concentrated by the imaging lens.

[0012] The present invention also proposes an ultrafast laser processing method for an aperture micro-aperture, which uses the above-mentioned ultrafast laser processing system for an aperture micro-aperture. The ultrafast laser processing method includes the following steps:

[0013] Place the metal sheet to be processed on the translation table;

[0014] The ultrafast laser beam emitted by the ultrafast laser pulse generator is focused on the metal sheet to be processed after transmission and beam reduction;

[0015] Set the processing parameters and procedures according to the size of the micro-hole to be processed and proceed with the processing:

[0016] The diameter of the microhole to be processed is φ; if φ ≥ 40 μm, the microhole processing is carried out by laser ring scanning;

[0017] If 16μm≤φ<40μm, first use the laser circular scanning method to process the groove with a thickness of 5μm-50μm, and then use the laser circular scanning method to process micro holes at the bottom of the groove;

[0018] If φ is less than 16μm, first use the laser ring scanning method to process the groove with a thickness of 5μm-50μm, and then switch to the laser punching method to process micro holes at the bottom of the groove.

[0019] The ultrafast laser processing method for aperture microapertures according to the present invention utilizes high-repetition-rate ultrafast laser pulses for circular rotary cutting or punching, improving processing precision, reducing the heat-affected zone, and preventing excessive melting and structural deformation of the metal sheet being processed. It also enhances the roundness of the aperture microapertures and the consistency of the inlet and outlet apertures. Furthermore, by flexibly controlling the ultrafast laser beam reduction factor, processing efficiency can be effectively improved while ensuring the processing quality of the aperture microaperture wall. Furthermore, the processing method of the present invention can achieve high-precision, high-quality processing of aperture microapertures of varying aperture diameters, meeting the diverse needs of apertures.

[0020] According to some embodiments of the present invention, the micro-hole processing using a laser circular scanning method includes: presetting a concentric circular scanning path, and scanning the metal sheet to be processed layer by layer with an ultrafast laser beam according to the scanning path.

[0021] According to some embodiments of the present invention, the switching to the laser processing mode includes: performing zooming on the ultrafast laser beam to change the diameter of the laser focus spot.

[0022] According to some embodiments of the present invention, the ultrafast laser processing method further includes: removing processing debris in real time during the processing.

[0023] According to some embodiments of the present invention, the ultrafast laser processing method further includes: monitoring a processing area of ​​the metal sheet to be processed in real time during the processing.

[0024] According to some embodiments of the present invention, the wavelength of the ultrafast laser beam is 1030 nm or 515 nm; the repetition frequency of the ultrafast laser beam is f, and satisfies 1 Hz ≤ f ≤ 100 kHz; the pulse width of the ultrafast laser beam is d, and satisfies 290 fs ≤ d ≤ 10 ps; the laser processing power of the ultrafast laser beam is P, and satisfies 0.1 W ≤ P ≤ 100 W.

[0025] According to some embodiments of the present invention, in the step of performing micro-hole processing using a laser circular scanning method, the scanning speed of the ultrafast laser beam is v, and satisfies 10 mm / s≤v≤1000 mm / s.

[0026] According to some embodiments of the present invention, in the step of performing micro-hole processing by laser circular scanning, the layer interval of the circular scanning is h, and satisfies 1 μm≤h≤20 μm.

[0027] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0029] Figure 1 is a schematic structural diagram of an ultrafast laser processing system according to some embodiments of the present invention;

[0030] Figure 2 is a schematic structural diagram of a positioning fixture according to some embodiments of the present invention;

[0031] Figure 3 is a schematic diagram of a first type of hole in an ultrafast laser processing method according to some embodiments of the present invention;

[0032] Figure 4 Schematic diagram of a third type of hole in an ultrafast laser processing method according to some embodiments of the present invention.

[0033] Reference numerals:

[0034] Ultrafast laser pulse generator 1; shutter 2; neutral density energy attenuator 3; first reflector 4; zoom lens 5; second reflector 6; focusing objective lens 7; imaging light source 8; semi-transparent and semi-reflective beam splitter 9; imaging lens 10; CCD camera 11; laser measurement light source 12; translation stage 13; metal sheet to be processed 14; positioning fixture 15; upper clamping block 151; lower clamping block 152; fastening bolt 153; chip removal regulator 16; chip removal fan 17; intelligent control card 18; computer and software control system 19; first microhole 20; sink 21; second microhole 22. DETAILED DESCRIPTION

[0035] Embodiments of the present application are described below in detail with reference to the accompanying drawings, wherein like or similar elements are denoted by the same or similar reference signs throughout the drawings. The embodiments described below are exemplary only, and are not to be understood as limiting the present application.

[0036] Reference is made below to Figures 1-4 The application further provides an ultrafast laser processing system for processing a micro-aperture of a diaphragm, and an ultrafast laser processing method.

[0037] The application further provides an ultrafast laser processing system for processing a micro-aperture of a diaphragm, and an ultrafast laser processing method. The ultrafast laser processing system for processing a micro-aperture of a diaphragm comprises a displacement table 13, a laser assembly, an imaging monitoring assembly, a laser ranging assembly, and a cleaning assembly. A metal sheet 14 to be processed is arranged on the displacement table, and the displacement table 13 is adapted to drive the metal sheet 14 to move along a processing path. The laser assembly comprises an ultrafast laser pulse generator 1, a mirror, a neutral density energy attenuation sheet 2, a variable magnification beam reducer 5, and a focusing objective lens 7. The ultrafast laser pulse generator 1 is adapted to emit an ultrafast laser beam. The mirror is adapted to adjust a transmission path of the ultrafast laser beam, so as to reflect the ultrafast laser beam to the metal sheet 14 to be processed. The neutral density energy attenuation sheet 2, the variable magnification beam reducer 5, and the focusing objective lens 7 are arranged in the transmission path of the ultrafast laser beam, so as to adjust characteristic parameters of the ultrafast laser beam. The imaging monitoring assembly is adapted to monitor a processing procedure of the metal sheet 14 to be processed. The laser ranging assembly is adapted to detect a distance between a focal point of the ultrafast laser beam and the metal sheet 14 to be processed. The cleaning assembly is adapted to remove debris generated in the processing procedure of the metal sheet 14 to be processed.

[0038] The ultrafast laser processing system of the diaphragm micro-hole according to the application, the ultrafast laser beam emitted by the ultrafast laser pulse generator 1 is transmitted to the metal sheet 14 to be processed to realize the precise removal of the material. Among them, the ultrafast laser beam changes the transmission direction due to reflection when passing through the reflector; passes through the neutral density energy attenuation sheet 2, which can adjust the laser power to the required processing parameters; passes through the variable power beam condensing mirror 5, which can regulate the condensing multiple of the ultrafast laser beam and change the spot size on the surface of the metal sheet 14 to be processed, so as to regulate the laser processing efficiency and processing precision; passes through the focusing objective 7, which focuses the ultrafast laser beam to form a high-energy-density focal point, thereby realizing the precise removal of the material. During processing, the displacement table 13 drives the metal sheet 14 to be processed to move, so as to realize the movement and scanning of the ultrafast laser beam on the surface of the metal sheet 14 to be processed. The heat accumulation generated by the processing of the metal sheet 14 to be processed can be reduced, thereby reducing the risk of thermal damage. The imaging light source 8 can be set to monitor the processing of the metal sheet 14 to be processed in real time, so as to adjust the processing strategy in time to avoid processing damage and processing deviation; the laser ranging assembly can be set to detect the distance between the focal point of the ultrafast laser beam and the metal sheet 14 to be processed in real time, so as to accurately monitor the position of the focal point of the ultrafast laser beam, so as to adjust the focal point of the ultrafast laser beam to be always on the processing surface of the metal sheet 14 to be processed; the cleaning assembly can be set to remove the metal residues generated during processing in real time, so as to avoid the influence of the metal residues on the interaction between the laser and the metal sheet 14 to be processed, avoid the influence of the residues on the processing quality, inhibit the re-solidification of the molten material, and further reduce the adhesion between the molten material and the hole wall, thereby reducing the thickness of the recast layer.

[0039] The ultrafast laser processing system of the diaphragm micro-hole according to the application, the laser assembly cooperates with the displacement table 13 to realize movement and scanning processing, which can realize the flexible regulation of the laser parameters during processing and ensure the consistency and repeatability of the diaphragm micro-hole processing. At the same time, the laser assembly can improve the processing efficiency by regulating the ultrafast laser beam. In addition, by setting the imaging monitoring assembly, the laser ranging assembly and the cleaning assembly, the processing roundness of the diaphragm micro-hole can be improved, the surface quality of the diaphragm micro-hole and the control of the heat-affected zone can be realized, and the processing quality of the ultrafast laser beam can be ensured.

[0040] In some embodiments, the laser assembly further comprises a shutter 2 and is provided with a first reflector 4 and a second reflector 6; wherein the shutter 2 is arranged on the transmission path of the ultrafast laser beam and is adapted to control the on-off of the ultrafast laser beam. As shown in the figure, Figure 1As shown, the light path of the ultrafast laser beam is as follows: the ultrafast laser pulse generator 1 emits an ultrafast laser beam, which first passes through the shutter 2, then passes through the neutral density energy attenuation sheet 23, and the ultrafast laser beam after power adjustment is reflected and guided by the first mirror 4, then changes the spot diameter by the variable power beam expander 5, and the ultrafast laser beam after beam expansion is reflected and guided by the second mirror 6, and is focused by the focusing objective 7 and projected onto the surface of the metal sheet 14 to be processed.

[0041] In some embodiments, the displacement table 13 is configured as a six-degree-of-freedom precision displacement table 13, which can realize movement in any direction to meet the scanning movement of the ultrafast laser beam on the surface of the metal sheet 14 to be processed and realize the deep processing of the aperture micro-hole. Further, the six-degree-of-freedom precision displacement table 13 is provided with a positioning clamp 15 for fixing the metal sheet 14 to be processed. As shown in Figure 2 As shown, the metal sheet to be processed is fixed on the positioning clamp 15; the positioning clamp 15 includes an upper clamp block 151 and a lower clamp block 152, and the metal sheet 14 to be processed is placed between the upper clamp block 151 and the lower clamp block 152 and is locked and fixed by the fastening bolt 153. Further, as shown in Figure 2 As shown, the middle part of the upper clamp block 151 and the lower clamp block 152 is formed with a clearance hole, and the clearance hole of the upper clamp block 151 can allow the ultrafast laser beam to pass through and directly irradiate on the surface of the metal sheet to be processed; the clearance hole of the lower clamp block 152 can make the products such as part of the debris generated by laser processing timely separate from the processing site, so as to avoid affecting the subsequent manufacturing process. The positioning clamp 15 of the present embodiment can ensure the positioning accuracy of the aperture micro-hole processing. The positioning clamp 15 is placed on the six-degree-of-freedom precision displacement table 13, and the position and movement of the metal sheet 14 to be processed in the X-axis, Y-axis and Z-axis directions can be accurately controlled by controlling the six-degree-of-freedom precision displacement table 13, so as to realize the accurate control of the laser processing position.

[0042] In some embodiments, the variable power beam expander 5 is configured as an electric variable power beam expander, which is controlled by an electric mode.

[0043] In some embodiments, the laser ranging assembly includes a laser measuring light source 12, which emits a ranging laser. By precisely controlling the emission and reception of the laser, combined with time / phase measurement technology, high-precision and high-efficiency distance detection is realized.

[0044] In some embodiments, the cleaning assembly includes a debris removal fan 17 and a debris removal controller 16. The debris removal fan 17 can blow air to the metal sheet 14 to be processed during the processing process to blow away the metal debris generated during the processing process. The debris removal controller 16 controls the debris removal fan 17 to adjust the air volume and direction of the debris removal fan 17.

[0045] According to some embodiments of the present invention, the ultrafast laser processing system for an aperture microaperture further includes a control assembly adapted to control the translation stage 13, the laser assembly, and the cleaning assembly, and adapted to receive monitoring data from the imaging monitoring assembly and the laser ranging assembly. Specifically, the control assembly includes an intelligent control card 18 and a computer and software control system 19. The ultrafast laser pulse generator 1, shutter 2, zoom lens 5, imaging monitoring assembly, laser measurement light source 12, six-degree-of-freedom precision translation stage 13, and chip removal controller 16 are coordinated and controlled by the intelligent control card 18 and the computer and software control system 19, ensuring high-precision, high-quality processing and manufacturing of the precision aperture microaperture.

[0046] According to some embodiments of the present invention, the imaging monitoring assembly includes an imaging light source 8, a semi-transparent and semi-reflective mirror 9, an imaging lens 10, and a CCD camera 11; the imaging light source 8 is suitable for emitting imaging light to the metal sheet 14 to be processed, and the imaging light source 8 is arranged on the same optical axis as the focusing objective lens 7, and the focusing objective lens 7 is suitable for focusing the imaging light; the semi-transparent and semi-reflective mirror 9 is suitable for the imaging light to pass through and is suitable for reflecting the reflected light of the imaging light; the imaging lens 10 is suitable for focusing the light reflected by the semi-transparent and semi-reflective mirror 9; and the CCD camera 11 is suitable for receiving the light concentrated by the imaging lens 10. In this embodiment, Figure 1 As shown, the imaging light source 8 emits imaging light toward the metal sheet 14 to be processed. The imaging light passes through the semi-transparent and semi-reflective mirror 9 and is focused by the focusing lens 7 before being projected onto the surface of the metal sheet 14 to be processed. The metal sheet 14 to be processed reflects the imaging light, and the reflected light is then projected onto the semi-transparent and semi-reflective mirror 9 via the focusing lens 7. The semi-transparent and semi-reflective mirror 9 reflects the reflected light again, and the reflected light is then focused by the imaging lens 10 and projected onto the CCD camera 11. The CCD camera 11 receives the reflected light and uses it for imaging processing and analysis to achieve real-time observation of the processing process and the processing results. The imaging light and the ultrafast laser beam are focused by the common focusing lens 7, which ensures that the laser focus and the imaging focus are consistent, thereby ensuring the accuracy of monitoring. Furthermore, the adjustment of the translation stage can simultaneously achieve that the laser focus and the imaging focus are located on the processing surface of the metal sheet 14 to be processed, thereby improving the control efficiency.

[0047] The present invention also proposes an ultrafast laser processing method for an aperture micro-aperture, which uses the above-mentioned ultrafast laser processing system for an aperture micro-aperture. The ultrafast laser processing method includes the following steps:

[0048] S1, placing the metal sheet 14 to be processed on the displacement stage 13;

[0049] S2, focusing the ultrafast laser beam emitted by the ultrafast laser pulse generator 1 on the metal sheet 14 to be processed after transmission and beam reduction;

[0050] S3. Set the processing parameters and procedures according to the size of the micro-hole to be processed and perform processing:

[0051] The diameter of the microhole to be processed is φ; if φ ≥ 40 μm, the microhole processing is carried out by laser ring scanning;

[0052] If 16μm≤φ<40μm, first use the laser ring scanning method to process the groove with a thickness of 5μm-50μm, and then use the laser ring scanning method to process micro holes at the bottom of the groove;

[0053] If φ is less than 16μm, first use the laser ring scanning method to process the groove with a thickness of 5μm-50μm, and then switch to the laser punching method to process micro holes at the bottom of the groove.

[0054] According to the ultrafast laser processing method for aperture microapertures of the present invention, the microapertures to be processed are classified into first, second, and third categories based on their aperture size. The aperture size of first-category apertures is greater than or equal to 40 μm, the aperture size of second-category apertures is less than 40 μm and greater than or equal to 16 μm, and the aperture size of third-category apertures is less than 16 μm. Aperture microapertures of different aperture sizes are processed differently, specifically with a processable microaperture size range of 1-2000 μm. Ultrafast laser circular scanning is used to move the ultrafast laser beam across the surface of the metal sheet 14 to be processed. The ultrashort pulse characteristics of the ultrafast laser evenly distribute the laser energy across the processing area, significantly reducing the heat-affected zone (HAZ), minimizing thermal impact and heat accumulation in the processing area, improving processing accuracy and consistency, and avoiding deformation, thereby ensuring processing quality. For the second-category apertures, circular scanning is first used to process the recessed groove, followed by processing the microaperture at the groove bottom. This reduces the depth of the microaperture required for circular scanning processing, thereby improving microaperture processing quality to a certain extent. For the third type of holes, circular scanning processing is difficult to achieve directly. In this case, the groove is made by circular scanning and then the laser beam is focused on the same center position for tapping punching. This can reduce the punching depth and help improve the quality of micro-hole processing.

[0055] The ultrafast laser processing method for aperture microapertures according to the present invention utilizes high-repetition-rate ultrafast laser pulses for circular-sweeping rotary cutting or punching, thereby improving processing accuracy, reducing the heat-affected zone, and preventing excessive melting and structural deformation of the metal sheet 14 being processed. It also improves the roundness of the aperture microapertures and the consistency of the inlet and outlet apertures. Furthermore, by flexibly controlling the ultrafast laser beam reduction factor, processing efficiency can be effectively improved while ensuring the processing quality of the aperture microaperture walls. Furthermore, the processing method of the present invention can achieve high-precision, high-quality processing of aperture microapertures of varying aperture diameters, meeting the diverse needs of apertures.

[0056] Before step S1, the ultrafast laser processing method for aperture micro-aperture of the present invention further includes a preparatory step, specifically including:

[0057] Build an ultrafast laser processing system for aperture micro-apertures. The ultrafast laser processing system is as described above, specifically including a translation stage 13, a laser component, an imaging monitoring component, a laser ranging component, and a cleaning component;

[0058] The surface of the metal sheet 14 to be processed is mechanically ground and polished, and then ultrasonically cleaned with deionized water and analytical pure ethanol in sequence to remove surface contaminants; the cleaned metal sheet is dried in an air environment and subjected to surface flattening treatment.

[0059] Furthermore, in step S1, after the metal sheet 14 to be processed is placed, the ultrafast laser processing method for aperture microapertures of the present invention also includes focusing light. Specifically, the imaging light source 8 is activated, so that the imaging light sequentially passes through the semi-transparent and semi-reflective beam splitter 9 and the focusing objective lens 7 to illuminate the surface of the metal sheet 14 to be processed. By adjusting the Z-axis height and the rotation angles of each axis of the six-degree-of-freedom precision translation stage 13, the light reflected from the surface of the metal sheet 14 to be processed is returned along the original optical path and projected onto the high-resolution CCD camera 11 after passing through the focusing objective lens 7, the semi-transparent and semi-reflective beam splitter 9, and the imaging lens 10. The high-resolution CCD camera 11 transmits the image in real time to the computer and software control system 19 via a data transmission line. When the image displayed by the computer and software control system 19 reaches optimal clarity, the focusing operation is completed.

[0060] In step S2, the laser pulse sequence emitted by the ultrafast laser pulse generator 1 passes through the shutter 2, the neutral density energy attenuation plate 2, the reflector, the electric zoom lens 5, and the focusing objective lens 7 in sequence and is focused and irradiated onto the surface of the metal sheet to be processed.

[0061] According to some embodiments of the present invention, laser circular scanning processing includes: presetting a concentric circular scanning path, and scanning the metal sheet 14 to be processed layer by layer with an ultrafast laser beam along the scanning path. In this embodiment, the ultrafast laser beam performs layer-by-layer circular scanning on the metal sheet 14 to be processed. By using a processing strategy of interlayer staggered scanning, the heat accumulation effect of adjacent scanning paths can be reduced, reducing thermal damage to the hole wall and the thickness of the recast layer. At the same time, the micropore roundness and micropore depth consistency and processing repeatability can be improved.

[0062] According to some embodiments of the present invention, switching to a laser processing mode includes: performing zooming and beam reduction on the ultrafast laser beam to change the diameter of the laser focus spot. In this embodiment, zooming and beam reduction can change the diameter of the ultrafast laser beam to adapt it to the processing aperture. This step can be achieved using the zoom and beam reduction lens 5 described above.

[0063] According to some embodiments of the present invention, the ultrafast laser processing method further includes: removing processing debris in real time during the processing process. In this embodiment, the real-time removal of metal debris generated during the processing can prevent the debris from affecting the interaction between the laser and the metal sheet sample, thereby preventing the debris from affecting the processing quality. It also inhibits the resolidification of the melt and further reduces the adhesion of the melt to the hole wall, thereby reducing the thickness of the recast layer, preventing the impact of debris on the processing quality, and improving the roundness and surface quality of the micro-hole processing. This step can be achieved using the above-mentioned cleaning component.

[0064] According to some embodiments of the present invention, the ultrafast laser processing method further includes: real-time monitoring of the processing area of ​​the metal sheet 14 to be processed during the processing process. In this embodiment, by real-time observation of the processing process and processing results, and analysis of the monitoring results, processing parameters can be adjusted promptly to improve processing quality. This step can be implemented using the aforementioned imaging monitoring component.

[0065] According to some embodiments of the present invention, during processing, the focus of the ultrafast laser beam should always be maintained within the processing area. This allows the energy of the ultrafast laser beam to be concentrated, increasing the energy density, thereby improving processing accuracy and reducing the heat-affected zone. This step can be specifically implemented by adjusting the movement of the focusing lens 7 and the translation stage 13 described above.

[0066] According to some embodiments of the present invention, when processing is performed, the wavelength of the ultrafast laser beam is 1030nm or 515nm; the repetition frequency of the ultrafast laser beam is f, and satisfies 1Hz≤f≤100kHz; the pulse width of the ultrafast laser beam is d, and satisfies 290fs≤d≤10ps; the laser processing power of the ultrafast laser beam is P, and satisfies 0.1W≤P≤100W. In this embodiment, limiting the wavelength, repetition frequency, pulse width and processing power of the ultrafast laser beam is the key to ensuring processing accuracy, quality and efficiency. The wavelength of the ultrafast laser beam of this embodiment is 1030nm or 515nm, which can adapt the wavelength to the material to be processed, optimize energy coupling, improve energy utilization, and reduce heat loss. The repetition frequency, pulse width and processing power of the ultrafast laser beam are limited to the above ranges, which can improve processing accuracy, reduce thermal effects, and improve processing quality.

[0067] According to some embodiments of the present invention, in the step of performing micro-hole processing using a laser circular scanning method, the scanning speed of the ultrafast laser beam is v, and satisfies 10mm / s≤v≤1000mm / s. It should be noted that when the scanning speed of the ultrafast laser beam is too high, it is easy to cause irregular holes and pores to form in the processing area, reducing the density; at the same time, it may cause the processing area to absorb less energy and accelerate the cooling and solidification rate, which is not conducive to micro-hole processing and forming. When the scanning speed of the ultrafast laser beam is too low, the heat-affected zone may increase, causing material deformation and reduced processing quality. In this embodiment, the scanning speed of the ultrafast laser beam is limited to the above range, which can ensure the processing quality of the aperture microhole.

[0068] According to some embodiments of the present invention, in the step of performing micro-hole processing by laser circular scanning, the layer spacing of the circular scanning is h, and satisfies 1μm≤h≤20μm. The layer spacing, that is, the scanning spacing, refers to the vertical distance between two adjacent scanning tracks when the ultrafast laser beam scans layer by layer. Too small a layer spacing may cause laser energy overlap, resulting in heat accumulation, which may cause material overheating, increase the recast layer or heat-affected zone. Too large a layer spacing may result in loose bonding between layers, resulting in rough hole walls, obvious step effects, and even defects. In this embodiment, the scanning layer spacing of the ultrafast laser beam is limited to the above range, which can ensure the processing quality of the aperture microhole.

[0069] In some embodiments, the ultrafast laser beam uses linearly polarized light, which can improve processing accuracy and processing quality.

[0070] The above embodiment can achieve high-quality processing of the micropore sidewall by regulating the scanning speed, layer spacing, and adjusting the laser processing frequency and energy, effectively suppress the formation of the recast layer, ensure the aperture accuracy and roundness, and ensure the consistency and repeatability of the processed micropores, thereby obtaining a high-precision aperture micropore structure that meets the strict requirements of the optical system.

[0071] According to some embodiments of the present invention, the ultrafast laser processing method for aperture micro-holes further includes the following steps:

[0072] S4. The processed aperture metal sheet is ultrasonically cleaned with deionized water and analytical grade ethanol in turn to remove powder residues during the processing.

[0073] The following processing tests were performed using the aforementioned ultrafast laser processing system and method:

[0074] Test 1: If Figure 3As shown, an aperture micropore with an aperture of 120 μm is processed using an ultrafast laser. The wavelength of the ultrafast laser is 1030 nm, the repetition frequency is 10 kHz, the pulse width is 290 fs, the laser processing power is 3 W, and the laser is linearly polarized light. A concentric annular scanning path is preset by a computer and software control system 19. The ultrafast laser beam scans layer by layer from the outside to the inside (or from the inside to the outside) at a speed of 100 mm / s along the predetermined path. The spacing between each layer is 10 μm. After each layer is processed, the six-degree-of-freedom precision translation stage 13 moves 5 μm upward along the Z axis, repeats the annular scanning process, and rotary cutting obtains a first micropore 20 with an aperture of 120 μm.

[0075] Test 2: If Figure 4 As shown, an aperture microaperture with an aperture of 15 μm is processed using an ultrafast laser. The wavelength of the ultrafast laser is 1030 nm, the repetition frequency is 10 kHz, the pulse width is 290 fs, the laser processing power is 3 W, and the laser is linearly polarized light. A concentric annular scanning path is preset by a computer and software control system 19. The ultrafast laser beam scans layer by layer from the outside to the inside (or from the inside to the outside) along the predetermined path at a speed of 100 mm / s, with a spacing of 10 μm between each layer. After each layer is processed, the six-degree-of-freedom precision translation stage 13 moves 5 μm upward along the Z axis, repeats the circular scanning process, and rotary cuts to obtain a groove 21 with a depth of 50 μm and an aperture of 200 μm. Subsequently, the six-degree-of-freedom precision translation stage 13 is controlled to move along the X and Y axes so that the laser focus is located at the center of the groove 21. The laser repetition frequency is switched to 1 kHz and the processing power is switched to 5 W. The electric zoom lens 5 is adjusted to change the diameter of the laser focus spot. Then, a second microaperture 22 with an aperture of 15 μm is punched in situ by laser.

[0076] The aperture micropores obtained by the above tests were inspected and found to have high roundness and high geometric precision; good consistency between the inlet and outlet; good processing repeatability, and can be mass-produced with highly consistent performance parameters and quality standards.

[0077] It can be seen that the ultrafast laser processing system and ultrafast laser processing method of the present invention can indeed improve processing accuracy and processing quality, and can be widely used in technical fields such as high-power laser systems, electronic optical systems, space imaging equipment, precision instruments and scientific research, providing high-precision, high-quality metal aperture elements for these fields.

[0078] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0079] In the description of the present invention, "first feature" and "second feature" may include one or more of the features.

[0080] In the description of the present invention, "plurality" means two or more.

[0081] In the description of the present invention, a first feature being “on” or “under” a second feature may include the first and second features being in direct contact with each other, or the first and second features not being in direct contact with each other but being in contact with each other via another feature therebetween.

[0082] In the description of the present invention, “on”, “above” and “above” a first feature of a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.

[0083] Throughout this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "example," "specific example," or "some examples" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0084] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. An ultrafast laser processing method for aperture micro-holes, characterized in that: An ultrafast laser processing system for an aperture micro-aperture is used, and the ultrafast laser processing system for an aperture micro-aperture comprises: A displacement platform, on which the metal sheet to be processed is disposed, and adapted to drive the metal sheet to be processed to move along a processing path; A laser assembly comprising an ultrafast laser pulse generator, a reflector, a neutral density energy attenuator, a zoom lens, and a focusing objective lens; the ultrafast laser pulse generator is adapted to emit an ultrafast laser beam; the reflector is adapted to adjust a transmission path of the ultrafast laser beam so as to reflect the ultrafast laser beam toward the metal sheet to be processed; the neutral density energy attenuator, the zoom lens, and the focusing objective lens are disposed in the transmission path of the ultrafast laser beam so as to adjust characteristic parameters of the ultrafast laser beam; An imaging monitoring component, wherein the imaging monitoring component is suitable for monitoring the processing process of the metal sheet to be processed; a laser distance measuring component, adapted to detect the distance between the focus of the ultrafast laser beam and the metal sheet to be processed; A cleaning component, adapted to remove debris generated during the processing of the metal sheet to be processed; The ultrafast laser processing method comprises the following steps: Place the metal sheet to be processed on the translation table; An ultrafast laser beam emitted by an ultrafast laser pulse generator is focused on the metal sheet to be processed after transmission and beam reduction; wherein the wavelength of the ultrafast laser beam is 1030 nm or 515 nm; the repetition frequency of the ultrafast laser beam is f, and satisfies 1 Hz ≤ f ≤ 100 kHz; the pulse width of the ultrafast laser beam is d, and satisfies 290 fs ≤ d ≤ 10 ps; the laser processing power of the ultrafast laser beam is P, and satisfies 0.1 W ≤ P ≤ 100 W; Set the processing parameters and procedures according to the size of the micro-hole to be processed and proceed with the processing: The diameter of the microhole to be processed is φ; if φ ≥ 40 μm, the microhole processing is carried out by laser ring scanning; If 16μm≤φ<40μm, first use the laser circular scanning method to process the groove with a thickness of 5μm-50μm, and then use the laser circular scanning method to process micro holes at the bottom of the groove; If φ is less than 16μm, first use the laser ring scanning method to process the groove with a thickness of 5μm-50μm, and then switch to the laser punching method to process micro holes at the bottom of the groove.

2. The ultrafast laser processing method for aperture micro-holes according to claim 1, characterized in that: The imaging monitoring component includes: An imaging light source, the imaging light source being adapted to emit imaging light toward the metal sheet to be processed, the imaging light source being coaxially arranged with the focusing objective lens, and the focusing objective lens being adapted to focus the imaging light; a semi-transparent and semi-reflective beam splitter, the semi-transparent and semi-reflective beam splitter being adapted to allow the imaging light to pass through and to reflect the reflected light of the imaging light; an imaging lens adapted to focus the light reflected by the semi-transparent and semi-reflective beam splitter; A CCD camera is suitable for receiving the light gathered by the imaging lens.

3. The ultrafast laser processing method for aperture micro-holes according to claim 1, characterized in that: The micro-hole processing using the laser circular scanning method includes: presetting a concentric circular scanning path, and the ultrafast laser beam scans the metal sheet to be processed layer by layer according to the scanning path.

4. The ultrafast laser processing method for aperture micro-holes according to claim 1, characterized in that: The switching to the laser punching mode includes: performing zooming and beam reduction on the ultrafast laser beam to change the diameter of the laser focus spot.

5. The ultrafast laser processing method for aperture micro-holes according to claim 1, characterized in that: Also includes: During the machining process, the machining chips are removed in real time.

6. The ultrafast laser processing method for aperture micro-holes according to claim 1, characterized in that: Also includes: During the processing, the processing area of ​​the metal sheet to be processed is monitored in real time.

7. The ultrafast laser processing method for aperture micro-holes according to claim 3, characterized in that: In the step of performing micro-hole processing by laser circular scanning, the scanning speed of the ultrafast laser beam is v, and satisfies 10 mm / s≤v≤1000 mm / s.

8. The ultrafast laser processing method for aperture micro-holes according to claim 3, characterized in that: In the step of performing micro-hole processing by laser circular scanning, the layer interval of the circular scanning is h, and satisfies 1μm≤h≤20μm.

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