Laser light path control method and system for micro-hole machining

Abstract

The invention discloses a laser light path control method and system for micropore machining, and belongs to the technical field of laser precision machining, and the method comprises the steps: obtaining surface light feedback data of a to-be-machined area, judging the surface integrity based on the surface light feedback data, and generating a machining permission instruction when the judgment is passed; in response to the processing permission instruction, negative spatial angular dispersion distribution is preset for a laser beam to counteract positive dispersion distortion generated by subsequent scanning deflection, so that a to-be-processed light field of which the wavefront is subjected to space-time calibration is constructed; executing spiral scanning by using a to-be-processed light field, modulating pulse frequency based on real-time scanning linear velocity, and generating a cut-off signal when entering a track center singular region; plasma radiation characteristics in the scanning process are monitored, and an instruction for switching to a concentric ring pumping track from spiral scanning is generated when slag discharging blockage is recognized. According to the method, the plasma radiation characteristics in the scanning process are monitored, so that the process stability and the yield of deep hole machining are improved.

Description

Technical Field

[0001] This invention relates to the field of laser precision machining technology, and more particularly to a laser optical path control method and system for micro-hole machining. Background Technology

[0002] With the development of aerospace, microelectronic packaging, and fuel injection systems, extremely high requirements have been placed on the processing accuracy and inner wall quality of micro-holes with high aspect ratios. In existing micro-hole laser processing technologies, a galvanometer scanning system is typically used to drive the laser beam along a helical scanning trajectory or a rotary cutting path to remove material layer by layer.

[0003] In actual high-precision micro-hole machining, existing laser optical path control technology still has the following significant technical bottlenecks: When the laser beam is significantly deflected by the scanning galvanometer and field mirror, the refractive index difference and diffraction effect of the optical elements will inevitably introduce forward diffraction divergence, reducing the peak power density of the laser pulse. It will also cause unexpected heat-affected zones at the machining points at the edge of the scanning field of view, seriously affecting the contour accuracy of the micro-hole. In the existing open-loop control mode, the laser pulse is usually emitted at a fixed repetition frequency, while the linear velocity of the helical scanning decreases linearly with the decrease of the scanning radius, resulting in severe central heat accumulation. This easily causes overheating, pitting, or recast layer accumulation at the bottom of the micro-hole, making it impossible to guarantee the uniformity of the micro-hole depth. For the slag removal problem of high aspect ratio micro-holes, as the hole depth increases, the narrow hole diameter greatly restricts the diffusion channel of molten slag and plasma cloud. Existing technologies typically rely on passive auxiliary gas blowing or simple mechanical shutdown through-hole methods for slag removal, which can easily lead to slag accumulation at the bottom of the hole and blockage of the slag removal channel. This can then induce high pressure accumulation inside the hole and cause hole bursting, damaging the integrity of the micropore inner wall. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and provides a laser optical path control method and system for micro-hole processing.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a laser optical path control method and system for micro-hole processing, comprising:

[0006] Acquire surface light feedback data of the area to be processed, determine the surface integrity based on the surface light feedback data, and generate a processing permission instruction when the determination is passed.

[0007] In response to the processing permission instruction, a negative spatial dispersion distribution is preset for the laser beam to counteract the positive dispersion distortion caused by subsequent scanning deflection, thereby constructing a wavefront-temporally calibrated optical field to be processed.

[0008] Helical scanning is performed using the optical field to be processed, the pulse frequency is modulated based on the real-time scanning linear velocity, and a cutoff signal is generated when entering the singular region at the center of the trajectory.

[0009] The plasma radiation characteristics during the scanning process are monitored, and when slag blockage is detected, an instruction is generated to switch from helical scanning to concentric ring pump trajectory.

[0010] In a preferred embodiment of the present invention, acquiring surface light feedback data of the area to be processed includes:

[0011] The laser beam is controlled to scan the area to be processed along a preset detection scanning path with a pulse energy density lower than the material ablation threshold, and the reflection signal is collected in real time.

[0012] Calculate the reflectivity variance of the reflected signal and use the reflectivity variance as the surface light feedback data;

[0013] The determination of surface integrity based on the surface light feedback data includes: comparing the reflectance variance value with a preset rejection threshold; if the reflectance variance value is less than or equal to the rejection threshold, the surface integrity is determined to be passed.

[0014] In a preferred embodiment of the present invention, the step of presetting the negative spatial angular dispersion distribution of the laser beam includes: determining the positive diffraction angular dispersion introduced by performing the scanning deflection action at the center operating frequency;

[0015] Configure dispersion compensation parameters to generate negative group velocity dispersion and negative spatial dispersion that are equal in magnitude and opposite in direction to the positive diffraction dispersion, so that after the laser beam is deflected at a large angle, the spectral components re-overlap in the spatiotemporal domain.

[0016] In a preferred embodiment of the present invention, the step of modulating the pulse frequency based on real-time scanning linear velocity includes:

[0017] A real-time mapping function between the laser pulse repetition frequency and the scanning line velocity is established; the real-time mapping function is configured such that the laser pulse repetition frequency is directly proportional to the scanning line velocity and inversely proportional to the spot diameter.

[0018] During the helical scanning process, the real-time scanning linear velocity is substituted into the real-time mapping function to calculate the target pulse repetition frequency at the current moment, and the pulse emission frequency parameters of the laser beam are adjusted accordingly.

[0019] In a preferred embodiment of the present invention, generating a cutoff signal upon entering the singular region at the center of the trajectory includes:

[0020] A preset minimum speed threshold is defined, which corresponds to the central heat accumulation region of the spiral scanning trajectory.

[0021] The real-time scan line velocity is compared with the minimum speed threshold in real time.

[0022] When the real-time scanning line speed is less than the minimum speed threshold, the electro-optic modulation mechanism is triggered to perform a light-off action until the real-time scanning line speed recovers to above the minimum speed threshold.

[0023] In a preferred embodiment of the present invention, monitoring the plasma radiation characteristics during the scanning process includes:

[0024] Simultaneously acquire the intensity values ​​of metal spectral lines and oxide spectral lines in the plasma radiation signal;

[0025] A two-dimensional processing phase space is constructed with the metal spectral line intensity values ​​as the abscissa and the oxide spectral line intensity values ​​as the ordinate.

[0026] Tracking the real-time state point trajectory in the two-dimensional processing phase space, when the real-time state point trajectory deviates from the preset stable attractor region and the oxide spectral line intensity value exhibits high-frequency scintillation characteristics, it is determined that there is slag discharge blockage.

[0027] In a preferred embodiment of the present invention, the instruction for switching from helical scan to concentric ring pump trajectory includes:

[0028] While maintaining laser output, interrupt the current spiral feed path data stream and seamlessly switch to the concentric circle high-speed scanning path data stream;

[0029] The concentric high-speed scanning path induces a plasma shock wave, and the pressure gradient generated by the plasma shock wave removes the obstruction from the hole.

[0030] In a preferred embodiment of the present invention, after generating the instruction to switch from helical scan to concentric ring pump trajectory, the method further includes:

[0031] After the machining task is completed, the actual hole profile is scanned using a low-energy beam; the radial residual vector field between the actual hole profile and the standard design profile is calculated;

[0032] Identify regions in the radial residual vector field whose magnitude exceeds a preset accuracy threshold, and generate discrete point-to-point trimming paths for these regions until the residual returns to zero.

[0033] In a preferred embodiment of the present invention, after generating the instruction to switch from helical scan to concentric ring pump trajectory, the method further includes:

[0034] During the slag removal process using the concentric high-speed scanning path, the plasma radiation characteristics are continuously monitored.

[0035] When the intensity value of the oxide spectral line is detected to decrease to the steady-state range and the slag discharge blockage is determined to be resolved, a reset command is generated.

[0036] In response to the reset command, the control scanning path seamlessly switches from the concentric ring pump trajectory back to the spiral scanning trajectory to continue executing the unfinished micro-hole machining task.

[0037] In a preferred embodiment of the present invention, a laser optical path control system for micro-hole processing includes:

[0038] The pre-inspection module is configured to acquire surface light feedback data of the area to be processed, determine the surface integrity based on the surface light feedback data, and generate a processing permission instruction when the determination is passed.

[0039] The control module is configured to respond to the processing permission command by controlling the optical elements to pre-set a negative spatial dispersion distribution on the laser beam to counteract the positive dispersion distortion caused by subsequent scanning deflection, thereby constructing a wavefront-temporally calibrated optical field to be processed.

[0040] The control module is configured to perform helical scanning using the light field to be processed, modulate the pulse frequency based on the real-time scanning linear velocity, and generate a cutoff signal when entering the singular region at the center of the trajectory.

[0041] The state switching module is configured to monitor the plasma radiation characteristics during the scanning process and generate an instruction to switch from helical scanning to concentric ring pump trajectory when slag blockage is detected.

[0042] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0043] (1) This invention achieves the organic combination of wavefront calibration in the optical dimension and adaptive fluid pumping in the processing dimension by presetting the negative spatial dispersion distribution of the laser beam in response to the processing permission command and combining it with the plasma radiation characteristics monitored during the scanning process to generate a command to switch from spiral scanning to concentric ring pump trajectory when slag blockage is identified. This solves the problem of spatiotemporal dispersion distortion caused by high-speed scanning deflection, ensures the wavefront consistency of the optical field to be processed, and overcomes the technical problem of slag blockage leading to hole bursting in the micro-hole processing of aspect ratio. Thus, while significantly improving the hole forming accuracy and inner wall smoothness of micro-hole processing, it also greatly improves the process stability and yield of deep hole processing.

[0044] (2) The present invention adopts the technique of pre-setting negative spatial chromatic dispersion distribution of laser beam. By configuring dispersion compensation parameters, negative group velocity dispersion and negative spatial chromatic dispersion are generated that are equal in magnitude and opposite in direction to the positive diffraction chromatic dispersion introduced by scanning deflection. This makes the spectral components of the laser beam re-overlap in the spatiotemporal domain after large-angle deflection, eliminating the phenomenon of pulse leading edge tilt and ensuring that the laser pulse reaching the material surface always maintains the transformation limit state. Compared with the prior art, which only focuses on geometric focusing and ignores the spatiotemporal dispersion effect, resulting in defects such as pulse broadening, peak power reduction and heat-affected zone expansion at the edge of the scanning field of view, the method of the present invention effectively realizes the beam quality consistency control in the entire scanning field, ensuring that the cold processing effect of uniformity and no thermal damage can be maintained no matter what angle the beam is deflected to, which greatly improves the contour accuracy of deep hole processing.

[0045] (3) This invention utilizes the plasma radiation characteristics during the monitoring and scanning process and generates an instruction to switch from spiral scanning to concentric ring pumping trajectory when slag blockage is detected. It constructs a real-time feedback loop based on plasma radiation characteristics and realizes instantaneous switching from material etching mode to fluid pumping mode. Compared with the passive slag removal method that usually adopts shutdown mechanical through hole or relies solely on auxiliary gas blowing in the prior art, the method of this invention actively utilizes the shock wave power generated by the interaction between light and matter to complete the adaptive cleaning of deep hole blockage without interrupting the processing process and without introducing external tools. It effectively avoids the risk of hole bursting caused by sudden increase in pressure inside the hole and significantly improves the continuity of micro-hole processing and hole formation yield.

[0046] (4) The present invention also constructs a closed-loop control system for the entire process by acquiring surface light feedback data of the area to be processed and generating a processing permission instruction when the processing is deemed to be passed, as well as by using technical measures such as real-time scanning linear velocity modulation of pulse frequency and generating a cutoff signal when entering the singular region of the trajectory center. This avoids invalid processing on defective substrates from the source. On the other hand, by establishing a real-time mapping function between laser pulse repetition frequency and scanning linear velocity and a center blind zone cutoff strategy, the problem of uneven heat accumulation and energy deposition at the center of spiral scanning is solved. Based on the point-to-point trimming path generation mechanism of radial residual vector field, the present invention realizes the integrated integration from substrate detection before processing, dynamic energy control during processing to closed-loop accuracy compensation after processing, and completely solves the industry problem of uncontrollable geometric morphology and poor consistency of inner wall quality in the processing of micro-holes with high aspect ratio. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a flowchart illustrating the control method steps of the present invention;

[0049] Figure 2 This is a diagram illustrating the switching steps of the method of the present invention;

[0050] Figure 3 This is a system structure block diagram of a preferred embodiment of the present invention; Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0053] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0054] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0055] Application Overview:

[0056] In the field of laser micro-nano fabrication technology, especially in the processing of high aspect ratio micro-holes, there has always been a difficult contradiction between processing efficiency and hole quality. Although traditional rotary cutting improves the perpendicularity of the hole wall compared to single-pulse impact drilling, the large-angle deflection of the scanning galvanometer inevitably introduces positive dispersion distortion during high-frequency, fast scanning, leading to a deterioration of the spatiotemporal characteristics of the spot on the focal plane and consequently causing thermal damage to the processing area. More importantly, as the depth of the micro-hole increases, the slag removal channel within the narrow aperture is easily blocked by molten slag. If the original spiral scanning path is maintained and processing continues, it will cause a sudden increase in pressure inside the hole and even hole bursting. On the other hand, stopping the machine to remove slag significantly reduces processing efficiency. Currently, there is a lack of a control scheme that can maintain the beam wavefront quality while adapting to the blockage state inside the hole during high-speed dynamic scanning.

[0057] To address the aforementioned issues, this application provides a laser optical path control method and system for micro-hole machining. This solution actively counteracts the spatiotemporal distortion caused by the scanning galvanometer by pre-setting a negative spatial variability distribution at the front end of the optical path, ensuring the wavefront consistency of the optical field to be processed. Furthermore, it innovatively introduces a real-time feedback loop based on plasma radiation characteristics. Utilizing the plasma shock wave effect, it seamlessly switches the material removal mode to the fluid pumping mode when slag blockage is detected, thereby significantly improving the stability and success rate of deep hole machining while ensuring machining accuracy.

[0058] Example 1:

[0059] like Figure 1 As shown, this embodiment provides a laser optical path control method for micro-hole processing, which includes the following steps:

[0060] Acquire surface light feedback data of the area to be processed, determine surface integrity based on the surface light feedback data, and generate a processing permission instruction when the determination is passed.

[0061] In response to the processing permit order, a negative spatial dispersion distribution is preset on the laser beam to counteract the positive dispersion distortion caused by subsequent scanning deflection, thereby constructing a wavefront-temporally calibrated optical field to be processed.

[0062] Helical scanning is performed using the optical field to be processed, the pulse frequency is modulated based on the real-time scanning linear velocity, and a cutoff signal is generated when entering the singular region at the center of the trajectory.

[0063] The system monitors plasma radiation characteristics during the scanning process and generates a command to switch from helical scanning to concentric ring pump trajectory when slag blockage is detected.

[0064] In the practical engineering implementation of this method, translating the above theoretical steps into executable control logic presents a significant technical challenge. Since the positive diffraction variability introduced by scanning deflection is a nonlinear quantity that dynamically changes with the deflection angle, configuring static or dynamic optical elements to generate a precisely matched negative spatial variability distribution is a prerequisite for constructing a high-quality optical field to be processed. Secondly, under the action of extremely high-frequency laser pulses, the plasma radiation signal is mixed with a large amount of background noise and random fluctuations. The system must accurately extract the characteristic signals representing slag discharge blockage from the intensity changes of metal and oxide spectral lines within a microsecond-level time window and drive the scanning galvanometer to complete the inertia abrupt change from a helical trajectory to a concentric loop trajectory. This places extremely high demands on the robustness of the control algorithm and the dynamic response capability of the servo system. This embodiment effectively solves the above engineering problems by constructing a specific mapping function and phase space model.

[0065] In this embodiment of the invention, obtaining surface light feedback data of the area to be processed includes:

[0066] The laser beam is controlled to scan the area to be processed along a preset detection scanning path with a pulse energy density lower than the material ablation threshold, and the reflection signal is collected in real time.

[0067] Calculate the reflectivity variance of the reflected signal and use the reflectivity variance as surface light feedback data;

[0068] Determining surface integrity based on surface light feedback data includes: comparing the reflectance variance value with a preset rejection threshold; if the reflectance variance value is less than or equal to the rejection threshold, the surface integrity is determined to be acceptable.

[0069] The steps of acquiring surface light feedback data of the area to be processed and determining surface integrity based on the surface light feedback data are specifically achieved in the following way: controlling the laser beam to scan the area to be processed along a preset detection scanning path with a pulse energy density lower than the material ablation threshold, and acquiring the reflection signal in real time.

[0070] Wherein, pulse energy density below the material ablation threshold refers to a non-destructive detection energy mode whose energy density is insufficient to cause melting, vaporization or any permanent damage to the surface of the material being processed; preferably, the pulse energy density can be pre-calibrated and set to between 10% and 50% of the known ablation threshold of the specific material at the current laser wavelength and pulse width.

[0071] The preset detection scanning path aims to achieve rapid and uniform coverage of the entire area to be processed. Preferably, the detection scanning path can be generated as a Lissajous trajectory by configuring the galvanometer scanning parameters; a Lissajous trajectory is a planar closed curve synthesized by two mutually perpendicular simple harmonic vibrations, which has the advantage of being able to fill a rectangular or circular area with high density with a non-repeating path, thereby obtaining statistically representative surface state information in a short time.

[0072] The real-time acquisition of reflected signals can be achieved through a high-speed photodiode detector coaxially arranged with the main processing optical path. This detector is used to receive the probe laser beam reflected from the material surface, convert its light intensity signal into a corresponding voltage or current signal, calculate the reflectivity variance value of the reflected signal, and use the reflectivity variance value as surface light feedback data.

[0073] Specifically, the reflectivity variance value is obtained as follows: First, the continuous voltage or current signal collected by the photodiode is discretized according to the spatial position on the scanning path to obtain a sequence of signal intensity values ​​for N sampling points. Then, the signal strength value of each sampling point is... Normalization is performed to obtain the reflectivity at the corresponding location. Finally, the variance of this set of reflectance data is calculated using the following formula. :

[0074]

[0075] in, This represents the final variance value of reflectance. Let be the surface reflectance of the i-th sampling point; is the average reflectance of all N sampling points; N is the total number of sample points collected in the entire processing area.

[0076] The calculation result of this formula is a quantitative indicator that physically characterizes the degree of uniformity of surface reflection in the area to be processed. An ideal surface that is flat, clean, and free of defects has a highly consistent reflectivity at all points, so its variance value approaches zero. Conversely, if there are defects such as scratches, contaminants, pits, or oxide layers on the surface, the reflectivity of these defective points will deviate significantly from the average value, thus increasing the calculated variance value.

[0077] Determining surface integrity based on surface light feedback data includes: comparing the reflectivity variance value with a preset rejection threshold; if the reflectivity variance value is less than or equal to the rejection threshold, the surface integrity is determined to be acceptable, and a processing permit instruction is generated.

[0078] The rejection threshold is a critical criterion used to distinguish between acceptable and unacceptable surfaces. Preferably, this rejection threshold can be determined by performing the aforementioned detection scans on known acceptable samples and samples known to have unacceptable defects before production, obtaining the statistical distribution of their reflectance variance values, and setting a value that can effectively distinguish between the two and has a sufficient confidence interval.

[0079] When the real-time calculated variance value is lower than the threshold, it indicates that the surface condition of the area to be processed is consistent with the good sample. The system then generates a processing permission instruction to authorize the initiation of subsequent high-energy ablation processing steps. Conversely, if the variance value is higher than the threshold, processing is refused, and an alarm may be triggered or the workpiece may be marked for re-inspection.

[0080] This embodiment utilizes a method based on subthreshold energy detection and reflectivity variance statistical analysis to perform a rapid and non-destructive inspection of the material surface before formal processing. Compared with the inefficiencies and lack of automation integration caused by relying on manual sampling or offline microscopic observation in existing technologies, the method of this invention enables online and fully automated surface integrity determination for each processing point, avoiding the scrapping of the final product caused by precision processing on a defective substrate from the source, and greatly improving the yield and process stability of micro-hole processing.

[0081] In this embodiment of the invention, the negative spatial angular dispersion distribution of the laser beam is preset, including: determining the positive diffraction angular dispersion introduced by performing the scanning deflection action at the center working frequency;

[0082] By configuring dispersion compensation parameters, negative group velocity dispersion and negative spatial dispersion are generated that are equal in magnitude and opposite in direction to the dispersion of the positive diffraction, so that after the laser beam is deflected at a large angle, the spectral components re-overlap in the spatiotemporal domain.

[0083] The step of presetting the negative spatial diffraction distribution of the laser beam aims to solve the problem of spatiotemporal distortion caused by spectral component separation in ultrashort pulse laser scanning processing. Specifically, it is achieved by determining the positive diffraction diffraction amount introduced at the center working frequency when performing the scanning deflection action.

[0084] The term "scanning deflection" refers to the physical phenomenon that when a laser beam passes through a scanning galvanometer system and a field lens, the deflection angles of different wavelengths of light are inconsistent due to differences in the refractive index or diffraction effects of different spectral components in the optical medium.

[0085] The center operating frequency refers to the peak wavelength position of the energy distribution of the laser output pulse spectrum; preferably, the forward diffraction divergence can be obtained by simulation calculation through the construction of a ray tracing model of the optical system.

[0086] Specifically, the calculation logic is as follows: A physical model of the scanning galvanometer and field lens is established in the optical simulation software. The center wavelength and spectral width of the laser pulse are input, and the optical path trajectory of the beam when it is incident at the maximum scanning angle is simulated. The spatial separation distance and angular deviation between the edge wavelength rays and the center wavelength rays on the focal plane are calculated. This deviation value is quantified as the forward diffraction chromatic aberration. The effect of this step is to accurately quantify the inherent dispersion distortion of the optical system, providing a precise numerical reference for subsequent compensation.

[0087] Configure dispersion compensation parameters to generate negative group velocity dispersion and negative spatial dispersion, which are equal in magnitude and opposite in direction to the positive diffraction dispersion.

[0088] Specifically, configuring dispersion compensation parameters refers to adjusting the geometric parameters located at the front end of the optical path.

[0089] Specifically, the parameter configuration follows the logical relationship as follows:

[0090] ,

[0091] in, This represents the total amount of negative dispersion that needs to be introduced for dispersion pre-compensation; The positive diffraction role divergence introduced by the optical scanning system determined in the preceding steps; The magnification of the beam expander system.

[0092] Based on this logic, by finely adjusting the vertical spacing between grating pairs or the insertion depth of prisms, and introducing a preset negative group velocity dispersion into the optical path, that is, the high-frequency components propagate faster than the low-frequency components and the negative spatial group velocity dispersion, the spectral components are pre-spread out in reverse in space. Thus, before the beam enters the scanning galvanometer, a wavefront state that is completely mirror-reversed with the subsequent distortion is preset, so that after the laser beam undergoes a large-angle deflection, the spectral components re-overlap in the spatiotemporal domain.

[0093] This step, through the aforementioned preset compensation, ensures that when the laser pulse is transmitted to the focal plane of the scanning field lens, the previously preset negative dispersion is precisely filled by the positive dispersion generated by the scanning deflection. This allows the various spectral components, which were originally separated in time and space due to dispersion, to achieve spatiotemporal synchronous focusing at the moment they reach the processing point, eliminating the phenomenon of pulse leading edge tilt and restoring the original ultrashort pulse width and extremely high peak power density of the laser pulse.

[0094] This embodiment achieves consistent beam quality control across the entire scanning field through a dispersion management and wavefront calibration method based on pre-distortion and post-reduction principles. Compared to existing technologies that focus only on geometric focusing while neglecting spatiotemporal dispersion effects, resulting in defects such as pulse broadening, peak power reduction, and thermally affected zone expansion at the edge of the scanning field of view, the method of this invention ensures that the pulse reaching the material surface remains in the transformation limit state regardless of the angle to which the beam is deflected. This achieves a uniform, heat-damage-free cold working effect across the entire micro-hole machining range, significantly improving the contour accuracy and inner wall smoothness of deep hole machining.

[0095] In this embodiment of the invention, the pulse frequency is modulated based on the real-time scanning linear velocity, including:

[0096] Establish a real-time mapping function between laser pulse repetition frequency and scanning linear velocity; the real-time mapping function is configured such that the laser pulse repetition frequency is directly proportional to the scanning linear velocity and inversely proportional to the spot diameter.

[0097] During the helical scanning process, the real-time scanning linear velocity is substituted into the real-time mapping function to calculate the target pulse repetition frequency at the current moment, and the pulse emission frequency parameters of the laser beam are adjusted accordingly.

[0098] The real-time mapping function is configured such that the laser pulse repetition frequency is directly proportional to the scanning linear velocity and inversely proportional to the spot diameter.

[0099] Preferably, the real-time mapping function is a control algorithm based on an equal pulse overlap rate model, which aims to ensure that the spatial distribution density of the laser spot on the material surface does not fluctuate with the change of scanning speed.

[0100] Specifically, this real-time mapping function can be expressed by the following mathematical model:

[0101] ,

[0102] Where f(t) represents the repetition frequency of the laser pulse to be output at the current time t; v(t) represents the real-time scanning linear velocity of the laser focus on the surface of the area to be processed at the current time; and D represents the effective diameter of the focused spot. This represents the preset target pulse overlap rate.

[0103] This formula allows the system to dynamically lock the number of pulses per unit length path, thereby ensuring that the cumulative energy density acting on the material surface remains constant.

[0104] During the helical scanning process, the real-time scanning linear velocity is substituted into the real-time mapping function to calculate the target pulse repetition frequency at the current moment, and the pulse emission frequency parameters of the laser beam are adjusted accordingly.

[0105] The real-time scanning linear velocity is preferably obtained by reading the encoder feedback data of the scanning galvanometer motor, performing differential operations on the real-time position coordinates of the X and Y axes, and calculating the magnitude of the synthesized velocity vector. The system collects the trajectory tangential velocity at the current moment with an extremely high sampling rate and passes it as an input variable to the above mapping function.

[0106] Specifically, the target pulse repetition frequency at the current moment is calculated as follows: the system monitors the current helical scanning radius r, and at the angular velocity... In a constant helical feed mode, the scan linear velocity v decreases linearly as the radius r decreases, that is:

[0107] ,

[0108] Substitute the value of the real-time decrease in linear velocity into the aforementioned formula:

[0109] ,

[0110] The calculation is performed; as the scanning path approaches the center from the edge of the micro-hole, the calculated f(t) will automatically decrease proportionally as v(t) decreases; the calculated f(t) is converted into a corresponding trigger pulse signal and sent to the acousto-optic modulator or seed source drive circuit of the laser to change the repetition frequency of the emitted light in real time.

[0111] This embodiment solves the problem of uneven energy deposition caused by changes in linear velocity during helical scanning by using a variable frequency control method based on speed feedback. Compared with the open-loop control method of fixed frequency + fixed angular velocity commonly used in the prior art, the latter will cause the number of pulses per unit area to increase exponentially when approaching the center of the helix, which will lead to serious defects such as heat accumulation, thickening of the recast layer, and even burn-through of the hole bottom. The method of this invention realizes adaptive energy regulation of fast scanning and slow scanning, ensuring a high degree of consistency in material removal rate from the hole opening to the hole bottom and from the edge to the center, which significantly improves the inner wall quality and morphological consistency of micro-hole processing.

[0112] In this embodiment of the invention, generating a cutoff signal upon entering the singular region at the center of the trajectory includes:

[0113] A preset minimum speed threshold is set, which corresponds to the central heat accumulation region of the spiral scan trajectory.

[0114] Real-time comparison of real-time scan line speed with minimum speed threshold;

[0115] When the real-time scanning line speed is less than the minimum speed threshold, the electro-optic modulation mechanism is triggered to perform a light-off action until the real-time scanning line speed recovers to above the minimum speed threshold.

[0116] The central heat accumulation region of the spiral scanning trajectory refers to the spatial region in which the spiral path approaches the geometric center, i.e., the radius r approaches 0. Due to the linear velocity decreasing linearly with the radius in the constant angular velocity scanning mode, the overlap rate of the laser pulse in a unit area increases exponentially, resulting in an uncontrollable heat accumulation physical region.

[0117] Preferably, the minimum velocity threshold can be obtained by determining the lowest pulse repetition frequency at which the laser can stably output, based on the laser's hardware characteristics. Combining the spot diameter D and the maximum pulse overlap rate that the material can withstand Using the formula:

[0118] The calculation yielded the result.

[0119] This threshold defines a safety boundary. When the scan speed is below this boundary, even if the frequency is reduced to the minimum, overheating cannot be avoided. Energy injection must be forcibly stopped, and the real-time scan line speed must be compared with the minimum speed threshold in real time.

[0120] Specifically, the comparison process is achieved as follows: a high-priority comparator module is set in the low-level logic of the field-programmable gate array of the motion controller; the comparator module synchronously receives the real-time speed feedback value from the galvanometer encoder and the minimum speed threshold pre-written into the register at microsecond clock cycles; whenever a new speed sample value arrives, the comparator module immediately performs a value magnitude determination and outputs the corresponding logic level signal, for example, outputting a high level when the speed is lower than the threshold, and outputting a low level otherwise.

[0121] When the real-time scanning line speed is less than the minimum speed threshold, the electro-optic modulation mechanism is triggered to perform a light-off action until the real-time scanning line speed recovers to above the minimum speed threshold.

[0122] Among them, the electro-optic modulation mechanism refers to the acousto-optic modulator or electro-optic modulator component located between the laser source and the scanning galvanometer, which has a fast response capability at the nanosecond level.

[0123] Performing the "light-off" action does not mean cutting off the power supply to the laser. Instead, it refers to changing the refractive index of the modulation crystal to instantly deflect the propagation path of the laser beam from the processing optical path to the internal beam collector, thereby physically blocking the high-energy beam from reaching the area to be processed.

[0124] This process continues until the scanning path leaves the central singularity area and the linear velocity rises back to a safe value. At this point, the system cancels the deflection command and resumes normal processing.

[0125] This embodiment effectively avoids the kinematic singularity effect of the spiral machining center by adopting a center blind zone cutoff control strategy based on speed threshold determination. Compared with the defects such as overheating pits, recast layer accumulation or substrate perforation at the bottom of micro-holes often caused by the inability to accurately control the energy density of the center point in the prior art, the method of this invention artificially forms a very short energy blank period in a very small center area and uses the thermal conduction effect to naturally smooth the area, thereby achieving a high degree of flatness and cleanliness of the bottom surface of the hole while ensuring the regularity of the overall morphology of the micro-hole.

[0126] Example 2:

[0127] In this embodiment of the invention, monitoring the plasma radiation characteristics during the scanning process includes:

[0128] Simultaneously acquire the intensity values ​​of metal spectral lines and oxide spectral lines in the plasma radiation signal;

[0129] A two-dimensional processing phase space is constructed with the metal spectral line intensity values ​​as the abscissa and the oxide spectral line intensity values ​​as the ordinate.

[0130] Track the real-time state point trajectory in the two-dimensional processing phase space. When the real-time state point trajectory deviates from the preset stable attractor region and the oxide spectral line intensity value shows high-frequency scintillation characteristics, it is determined that there is slag discharge blockage.

[0131] Synchronous acquisition refers to the signal acquisition system being synchronized with the laser pulse emission timing at the microsecond level, ensuring that only the radiation signal generated instantaneously by the laser acting on the material is acquired, eliminating ambient light noise. Preferably, the acquisition process can be achieved through a paraxial or coaxial integrated spectral acquisition module, which includes a dichroic mirror and a multi-channel bandpass filter.

[0132] Specifically, the intensity value of a metal spectral line refers to the integral value of the light intensity of the characteristic wavelength emitted by the processed matrix material during the de-excitation process of excited atoms.

[0133] Oxide spectral line intensity values ​​refer to the continuous spectrum or specific oxide molecular bands produced by materials under high-temperature oxidation conditions, such as the integral value of the broadband radiation of metal oxides in the 600nm-800nm ​​wavelength band.

[0134] A two-dimensional processing phase space is constructed with the intensity of metal spectral lines on the x-axis and the intensity of oxide spectral lines on the y-axis.

[0135] Among them, the two-dimensional processing phase space is a mathematical and geometric space used to describe the dynamic evolution of the micro-hole processing process.

[0136] Specifically, this mathematical geometric space is constructed as follows: a set of data collected at each time step $t$ is mapped to a state vector point on a Cartesian coordinate system. , where the x-axis corresponds to the current metal spectral line intensity and the y-axis corresponds to the current oxide spectral line intensity.

[0137] Within this space, as the machining depth increases and the internal environment of the hole changes, the state point... The continuous movement will form a state trajectory that can intuitively represent the stability of the processing process.

[0138] Track the real-time state point trajectory in the two-dimensional processing phase space. When the real-time state point trajectory deviates from the preset stable attractor region and the oxide spectral line intensity value shows high-frequency scintillation characteristics, it is determined that there is slag discharge blockage.

[0139] Here, the stable attractor region refers to the aforementioned state point under normal, unobstructed, and ideal processing conditions. The statistical distribution range that should fall within the phase space; preferably, the stable attractor region can be determined by performing Gaussian mixture model cluster analysis on historical data of the good product processing process to delineate an elliptical boundary region with 95% confidence.

[0140] When the real-time trajectory point moves out of the boundary of the ellipse, it is usually manifested as a drift in the y-axis direction where the oxide intensity increases, which is considered a deviation.

[0141] High-frequency scintillation refers to the dramatic fluctuations in the time domain of oxide signals.

[0142] Specifically, this feature is determined by calculating the proportion of the high-frequency component energy of the coefficient of variation of the oxide spectral line intensity within the sliding time window; if the calculated value exceeds the preset fluctuation threshold, it indicates that the molten slag in the hole cannot be discharged smoothly and thus causes turbulent rolling, which confirms that slag discharge blockage has occurred.

[0143] It should be noted that, in this embodiment, when monitoring the plasma radiation characteristics during the scanning process, the specific selection of synchronously acquiring the intensity values ​​of metal spectral lines and oxide spectral lines in the plasma radiation signal is a core prerequisite for achieving accurate identification of slag discharge blockage.

[0144] During the spiral scanning process of high aspect ratio micro-holes, the photo-induced plasma dynamics inside the micro-holes are extremely complex. If only the total light intensity of the plasma radiation signal is collected, the signal escape rate inside the hole will naturally decrease as the processing depth increases. The attenuation of the total light intensity and the signal changes caused by slag removal blockage will overlap, resulting in low system sensitivity, susceptibility to background noise interference, and inability to distinguish between normal oxidation and blockage accumulation.

[0145] This embodiment achieves orthogonal decoupling of physical states by simultaneously acquiring the intensity values ​​of metal and oxide spectral lines in the plasma radiation signal. The intensity value of the metal spectral line refers to the integral value of the light intensity of the characteristic wavelength emitted by the substrate material during the de-excitation process of excited atoms. It objectively characterizes the rate at which the laser pulse effectively ablates the fresh substrate and is a positive indicator of the normal material etching process. The intensity value of the oxide spectral line refers to the integral value of the light intensity of the continuous spectrum or specific oxide molecular band generated by the material under high-temperature oxidation. When the slag in the hole cannot be smoothly discharged and causes turbulent tumbling, the slag produces strong reverse toughening absorption for subsequent laser pulses, resulting in an abnormal surge in the intensity value of the oxide spectral line and exhibiting violent fluctuations in the time domain.

[0146] Only by acquiring the two specific values ​​with clear physical orientations can a rigorous two-dimensional processing phase space be constructed, with the metal spectral line intensity value as the abscissa and the oxide spectral line intensity value as the ordinate. This two-dimensional processing phase space eliminates the limitations of absolute threshold judgment, enabling the control system to track the real-time state point trajectory in the two-dimensional processing phase space. Utilizing the relative drift trend, that is, when the real-time state point trajectory deviates from the preset stable attractor region and the oxide spectral line intensity value exhibits high-frequency flickering characteristics, it accurately determines that slag discharge blockage exists. The phase space trajectory tracking method based on dual spectral line intensity values ​​can accurately capture the weak signal signs of slag blockage at the bottom of the micropore in the early stage, providing irreplaceable data support for the subsequent generation of instructions to switch from helical scanning to concentric ring pump trajectory.

[0147] This embodiment achieves lag-free perception of the complex fluid dynamics state inside deep hole machining. Compared with the shortcomings of existing technologies that rely solely on light intensity threshold judgment or acoustic monitoring, resulting in low sensitivity, susceptibility to background noise interference, and inability to distinguish between normal oxidation and blockage accumulation, the method of this invention introduces the phase space trajectory as a multi-dimensional feature descriptor, which can accurately capture the weak signal signs of slag blockage at the bottom of the microhole in the early stage. This provides an accurate decision basis for timely process switching, thereby effectively preventing quality accidents such as hole bursts and excessive recast layer on the hole wall.

[0148] In this embodiment of the invention, the instruction to switch from helical scan to concentric ring pump trajectory includes:

[0149] While maintaining laser output, interrupt the current spiral feed path data stream and seamlessly switch to the concentric circle high-speed scanning path data stream;

[0150] A plasma shock wave is induced by a high-speed scanning path of concentric circles, and the pressure gradient generated by the plasma shock wave is used to remove the obstruction from the hole.

[0151] Maintaining the laser emission state means that during the transient process of trajectory switching, no laser-off signal is sent to the laser, but the continuous emission of the pulse sequence is maintained to prevent the plasma cloud in the micro-hole from cooling and extinguishing due to the interruption of energy injection.

[0152] The spiral feed path data stream and the concentric circle high-speed scan path data stream refer to a series of discrete coordinate points (x, y) and corresponding timestamps t, which are digital signal sequences.

[0153] Preferably, seamless switching can be achieved through a hardware interrupt mechanism based on a field-programmable gate array (FPGA).

[0154] Specifically, the switching process is executed through the following logic: when the FPGA receives the slag removal command, it immediately suspends the currently executing spiral interpolation operation module and locks the position coordinates of the current galvanometer. Then, the pre-stored concentric circle trajectory generation algorithm is activated to... As the starting connection point, a set of concentric circle scan instructions with fixed radius and extremely high angular velocity are generated and overwritten with the original output buffer.

[0155] The process is completed within a microsecond time window, ensuring that the mechanical movement of the scanning galvanometer does not stop or vibrate, and inducing plasma shock waves by using a high-speed concentric scanning path.

[0156] The concentric high-speed scanning path refers to the laser focus no longer performing downward material removal cutting inside the micro-hole, but instead performing high-speed rotational scanning along the contour of the hole wall, with its linear velocity preferably set to be significantly higher than the material's sound velocity.

[0157] Induced plasma shock wave refers to the process of using laser energy to heat the plasma plume inside the hole, causing it to undergo reverse bremsstrahlung absorption and rapid expansion.

[0158] Specifically, when a high-repetition-rate, high-energy laser beam scans at high speed along a concentric circular trajectory, the laser energy is confined to a narrow space at the bottom of the micropore and heats the mixture of air and metal vapor to tens of thousands of degrees Celsius in a very short time, causing the gas pressure to rise instantaneously. This creates a high-pressure shock wave front that spreads outward at the bottom of the micropore, and the pressure gradient generated by the plasma shock wave removes the blockage from the pore.

[0159] The pressure gradient refers to the pressure difference vector field formed from the high-pressure shock wave region at the bottom of the borehole to the atmospheric pressure region at the borehole opening.

[0160] Specifically, the removal process follows the principle of photo-induced piston in fluid mechanics: due to the limitations of the micropore sidewalls and bottom, the rapidly expanding plasma shock wave cannot spread in all directions and can only be ejected upward along the pore axis; the high-speed airflow of this directional jet carries huge kinetic energy, forcibly engulfing the slag deposited at the bottom of the pore or adhering to the pore wall and ejecting it out of the pore. This process is similar to the piston exhaust stroke in an internal combustion engine, which can effectively clean micropore channels with a very large depth-to-diameter ratio.

[0161] This embodiment employs an in-situ mode-switching control strategy to instantly transform the role of laser processing from material etching to fluid pumping. Compared to the passive slag removal methods in existing technologies that typically involve stopping the machine to mechanically open holes or relying solely on auxiliary gas blowing, the method of this invention actively utilizes the shock wave dynamics generated by the interaction between light and matter to achieve adaptive cleaning of deep hole blockages without interrupting the processing or introducing external tools, significantly improving the continuity of micro-hole processing and the yield of hole formation.

[0162] In this embodiment of the invention, after generating the instruction to switch from helical scan to concentric ring pump trajectory, the method further includes:

[0163] After the machining task is completed, the actual hole profile is scanned using a low-energy beam; the radial residual vector field between the actual hole profile and the standard design profile is calculated.

[0164] Identify regions in the radial residual vector field whose magnitude exceeds a preset accuracy threshold, and generate discrete point-to-point trimming paths for these regions until the residual returns to zero.

[0165] The completion of the processing task refers to the state after the system has executed all the preset spiral scanning and concentric ring pumping commands, and the micropores have been initially formed.

[0166] Low-energy laser beams refer to laser beams used for detection whose energy density decays to below the material modification threshold; their function is illumination rather than etching.

[0167] Preferably, the actual borehole profile can be obtained by the following method: controlling the laser beam to perform a high-resolution circular scan along the inner wall of the microhole, while using a coaxial photodetector to record the spatial distribution of the reflected light intensity; based on the galvanometer coordinates corresponding to the abrupt change points of the reflected signal, combined with the principles of confocal microscopy or triangulation, the system reconstructs the closed geometric curve of the inner wall of the microhole on the focal plane, which is the actual borehole profile, and calculates the radial residual vector field between the actual borehole profile and the standard design profile.

[0168] The standard design profile refers to the pre-stored ideal circular or irregular aperture trajectory.

[0169] Specifically, the radial residual vector field is obtained as follows: a polar coordinate system is established with the geometric center of the micropore design as the origin, and the circumferential direction is discretized into M angular components, for example, taking a point every 1 degree; for each angle Calculate the actual contour radius With design contour radius The difference is used to construct the residual vector.

[0170] ,

[0171] in, In the angle The radial residual vector at the location; The measured radius of the hole wall; The theoretical radius; This is the unit direction vector along that angle.

[0172] The calculation process iterates through the entire circumference (k=1, 2, ..., M), all The set of these constitutes the radial residual vector field describing the distribution of micropore edge errors.

[0173] The effect of this step is to decouple the complex two-dimensional contour error into a series of quantized deviation values ​​distributed radially, providing an accurate data map for subsequent fine trimming; identifying regions in the radial residual vector field whose magnitude exceeds a preset accuracy threshold, and generating discrete point-to-point trimming paths for these regions until the residual returns to zero.

[0174] The preset accuracy threshold is the maximum allowable error value set based on the workpiece tolerance requirements.

[0175] Discrete point-to-point trimming path refers to a laser beam no longer performing continuous line scanning, but instead based on the residual vector. At non-zero positions, the driving galvanometer rapidly jumps between various error bumps, only transmitting pulses at fixed points in the error region for peak clipping.

[0176] Specifically, this process is a closed-loop iterative process: the system according to The number of pulses required to calculate the magnitude is then adjusted, and a low-energy scan and residual calculation are performed again. This process is repeated until the residual vector magnitude at all angles is lower than the preset accuracy threshold, at which point the residual is considered to be zero.

[0177] This embodiment solves the problem of out-of-tolerance hole dimensions caused by material inhomogeneity or beam drift in traditional open-loop machining modes by employing an in-situ measurement-based optical closed-loop compensation technology. Compared to the inefficient process in existing technologies, which typically requires removing the workpiece and repeatedly transferring it between offline measurement and machining equipment for finishing, the method of this invention achieves integrated processing, measurement, and compensation. Through a discretized point-to-point fixed-point clearing strategy, sub-micron level convergence of micro-hole contour accuracy is achieved without damaging the surface of the qualified area, significantly improving the final geometric quality of micro-machined products.

[0178] like Figure 2 As shown, in this embodiment of the invention, after generating the instruction to switch from helical scan to concentric ring pump trajectory, the method further includes:

[0179] During the slag removal process using a concentric high-speed scanning path, plasma radiation characteristics are continuously monitored.

[0180] When the intensity value of the oxide spectral line is detected to decrease to the steady-state range and the slag discharge blockage is determined to be resolved, a reset command is generated.

[0181] In response to a reset command, the control scan path seamlessly switches back from the concentric ring pump trajectory to the helical scan trajectory to continue executing unfinished micro-hole machining tasks.

[0182] Continuous monitoring refers to the photoelectric detection system maintaining a high-frequency sampling state synchronized with the laser pulse while performing fluid pumping operations, with the sampling frequency preferably not less than 100kHz.

[0183] This step aims to capture the feedback of the micropore internal environment on the cleaning action in real time; since the laser no longer etches the substrate material at this time, but acts on the residual slag and plasma cloud, the spectral signal will exhibit dynamic characteristics that are completely different from normal cutting.

[0184] When the intensity value of the oxide spectral line is detected to decrease to the steady-state range and the slag discharge blockage is determined to be resolved, a reset command is generated.

[0185] Here, the steady-state range refers to the range in which the intensity values ​​of the oxide spectral lines return to the background noise level or the stimulated emission level of a pure substrate; preferably, this steady-state range can be defined by setting a reference value. With fluctuation tolerance To determine, the interval is:

[0186] .

[0187] Specifically, the clearance of the slag discharge blockage is determined by the following method:

[0188] The system calculates the average intensity of oxide spectral lines within the sliding time window. If the conditions are met: Furthermore, the duration of this state exceeds the preset confirmation threshold. For example, if 50 pulse cycles are performed continuously, it is confirmed that the slag inside the hole has been completely removed and the environment has been restored to cleanliness.

[0189] At this point, the system triggers a reset command, which is a hardware interrupt signal used to terminate the current pump subroutine and call the main machining program. In response to the reset command, the control scan path seamlessly switches from the concentric ring pump trajectory back to the helical scan trajectory to continue executing the unfinished micro-hole machining task.

[0190] The seamless switching back to the spiral scan trajectory relies on a breakpoint resume mechanism based on stack memory.

[0191] Specifically, this mechanism is implemented as follows: at the initial moment when the system responds to the aforementioned switch to the concentric ring pump trajectory, the three-dimensional coordinates of the helical scan interruption point at that time have been set. The corresponding processing progress index number is pushed into the last-in-first-out stack composed of registers; when a reset command is received, the system first stops the output of concentric circle scan data, then pops the coordinate information of the interruption point from the stack, and quickly jumps the galvanometer position to... Subsequently, the spiral feed algorithm is reloaded to restore the interpolation calculation and output of subsequent path data from the breakpoint. This process ensures the strict spatial continuity of the processing trajectory and avoids repeated processing or missed processing.

[0192] This embodiment achieves intelligent return from abnormal handling to normal processing through a self-healing processing control strategy based on spectral feedback closed loop. Compared with the prior art, which often requires manual intervention to reset or rescan after slag removal, resulting in wasted time and positional alignment errors, the method of this invention can automatically complete the entire set of actions from monitoring to cleaning to verification to retransmission within milliseconds. This ensures both the thoroughness of slag removal inside the micropores and the maximum continuity of the inner wall of the final pore and the maximization of processing efficiency.

[0193] Example 3:

[0194] like Figure 3 As shown, in this embodiment of the invention, a laser optical path control system for micro-hole processing is provided, comprising:

[0195] The pre-inspection module is configured to acquire surface light feedback data of the area to be processed, determine the surface integrity based on the surface light feedback data, and generate a processing permission instruction when the determination is passed.

[0196] The control module is configured to respond to the processing permission command by controlling the optical elements to pre-set the negative spatial dispersion distribution of the laser beam to counteract the positive dispersion distortion caused by subsequent scanning deflection, thereby constructing a wavefront-space-calibrated optical field to be processed.

[0197] The control module is configured to perform helical scanning using the light field to be processed, modulate the pulse frequency based on the real-time scanning linear velocity, and generate a cutoff signal when entering the singular region at the center of the trajectory.

[0198] The state switching module is configured to monitor the plasma radiation characteristics during the scanning process and generate an instruction to switch from helical scanning to concentric ring pump trajectory when slag blockage is detected.

[0199] This system constructs a closed-loop control system covering the entire process from pre-process detection to in-process calibration to self-healing in case of anomalies, which significantly improves the yield, hole wall smoothness and process stability of micro-hole processing, and is particularly suitable for manufacturing requirements of high-quality micro-holes.

[0200] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A laser optical path control method for micro-hole fabrication, characterized in that, include: Acquire surface light feedback data of the area to be processed, determine the surface integrity based on the surface light feedback data, and generate a processing permission instruction when the determination is passed. In response to the processing permission instruction, a negative spatial dispersion distribution is preset for the laser beam to counteract the positive dispersion distortion caused by subsequent scanning deflection, thereby constructing a wavefront-temporally calibrated optical field to be processed. Helical scanning is performed using the optical field to be processed, the pulse frequency is modulated based on the real-time scanning linear velocity, and a cutoff signal is generated when entering the singular region at the center of the trajectory. The plasma radiation characteristics during the scanning process are monitored, and when slag blockage is detected, an instruction is generated to switch from helical scanning to concentric ring pump trajectory.

2. The laser optical path control method for micro-hole processing according to claim 1, characterized in that: The acquisition of surface light feedback data of the area to be processed includes: The laser beam is controlled to scan the area to be processed along a preset detection scanning path with a pulse energy density lower than the material ablation threshold, and the reflection signal is collected in real time. Calculate the reflectivity variance of the reflected signal and use the reflectivity variance as the surface light feedback data; The determination of surface integrity based on the surface light feedback data includes: comparing the reflectance variance value with a preset rejection threshold; if the reflectance variance value is less than or equal to the rejection threshold, the surface integrity is determined to be passed.

3. The laser optical path control method for micro-hole processing according to claim 1, characterized in that: The preset negative spatial angular dispersion distribution of the laser beam includes: determining the positive diffraction angular dispersion introduced by performing the scanning deflection action at the center working frequency; Configure dispersion compensation parameters to generate negative group velocity dispersion and negative spatial dispersion that are equal in magnitude and opposite in direction to the positive diffraction dispersion, so that after the laser beam is deflected at a large angle, the spectral components re-overlap in the spatiotemporal domain.

4. The laser optical path control method for micro-hole processing according to claim 1, characterized in that: The pulse frequency modulation based on real-time scan linear velocity includes: A real-time mapping function between the laser pulse repetition frequency and the scanning line velocity is established; the real-time mapping function is configured such that the laser pulse repetition frequency is directly proportional to the scanning line velocity and inversely proportional to the spot diameter. During the helical scanning process, the real-time scanning linear velocity is substituted into the real-time mapping function to calculate the target pulse repetition frequency at the current moment, and the pulse emission frequency parameters of the laser beam are adjusted accordingly.

5. The laser optical path control method for micro-hole processing according to claim 1, characterized in that: The step of generating a cutoff signal upon entering the singular region at the center of the trajectory includes: A preset minimum speed threshold is defined, which corresponds to the central heat accumulation region of the spiral scanning trajectory. The real-time scan line velocity is compared with the minimum speed threshold in real time. When the real-time scanning line speed is less than the minimum speed threshold, the electro-optic modulation mechanism is triggered to perform a light-off action until the real-time scanning line speed recovers to above the minimum speed threshold.

6. The laser optical path control method for micro-hole processing according to claim 1, characterized in that: The monitoring of plasma radiation characteristics during the scanning process includes: Simultaneously acquire the intensity values ​​of metal spectral lines and oxide spectral lines in the plasma radiation signal; A two-dimensional processing phase space is constructed with the metal spectral line intensity values ​​as the abscissa and the oxide spectral line intensity values ​​as the ordinate. Tracking the real-time state point trajectory in the two-dimensional processing phase space, when the real-time state point trajectory deviates from the preset stable attractor region and the oxide spectral line intensity value exhibits high-frequency scintillation characteristics, it is determined that there is slag discharge blockage.

7. The laser optical path control method for micro-hole processing according to claim 1, characterized in that: The instructions for generating the switch from helical scan to concentric ring pump trajectory include: While maintaining laser output, interrupt the current spiral feed path data stream and seamlessly switch to the concentric circle high-speed scanning path data stream; The concentric high-speed scanning path induces a plasma shock wave, and the pressure gradient generated by the plasma shock wave removes the obstruction from the hole.

8. The laser optical path control method for micro-hole processing according to claim 1, characterized in that: After generating the instruction to switch from helical scan to concentric ring pump trajectory, the method further includes: After the machining task is completed, the actual hole profile is scanned using a low-energy beam; the radial residual vector field between the actual hole profile and the standard design profile is calculated; Identify regions in the radial residual vector field whose magnitude exceeds a preset accuracy threshold, and generate discrete point-to-point trimming paths for these regions until the residual returns to zero.

9. A laser optical path control method for micro-hole processing according to claim 7, characterized in that: After generating the instruction to switch from helical scan to concentric ring pump trajectory, the method further includes: During the slag removal process using the concentric high-speed scanning path, the plasma radiation characteristics are continuously monitored. When the intensity value of the oxide spectral line is detected to decrease to the steady-state range and the slag discharge blockage is determined to be resolved, a reset command is generated. In response to the reset command, the control scanning path seamlessly switches from the concentric ring pump trajectory back to the spiral scanning trajectory to continue executing the unfinished micro-hole machining task.

10. A laser optical path control system for micro-hole processing, characterized in that, include: The pre-inspection module is configured to acquire surface light feedback data of the area to be processed, determine the surface integrity based on the surface light feedback data, and generate a processing permission instruction when the determination is passed. The control module is configured to respond to the processing permission command by controlling the optical elements to pre-set a negative spatial dispersion distribution on the laser beam to counteract the positive dispersion distortion caused by subsequent scanning deflection, thereby constructing a wavefront-temporally calibrated optical field to be processed. The control module is configured to perform helical scanning using the light field to be processed, modulate the pulse frequency based on the real-time scanning linear velocity, and generate a cutoff signal when entering the singular region at the center of the trajectory. The state switching module is configured to monitor the plasma radiation characteristics during the scanning process and generate an instruction to switch from helical scanning to concentric ring pump trajectory when slag blockage is detected.

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