High-speed precise marking equipment based on dual-wavelength laser system

Abstract

The invention belongs to the technical field of automatic control, and particularly relates to high-speed precise marking equipment based on a dual-wavelength laser system. The device comprises a projection control unit, a wavelength adaptive mapping unit and a marking control unit. The projection control unit is used for projecting multiband probe light to a to-be-marked area of a target surface and generating a wavelength priority queue corresponding to a material type; the wavelength adaptive mapping unit is used for generating an independent energy scheduling curve for each material according to the wavelength priority queue; and the marking control unit is used for converting a to-be-carved pattern into a continuous vector instruction stream, and by utilizing double-cavity synchronous threshold control, the first wavelength laser and the second wavelength laser act on the same marking track in a common light path of the scanning head in a cross time sequence. According to the method, the marking boundary definition and the overall consistency are effectively improved, and the machining quality and the machining efficiency of the system under the multi-material complex working condition are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of automatic control, and particularly relates to a high-speed precision marking device based on a dual-wavelength laser system. Background Art

[0002] At present, as a non-contact, programmable, and high-precision material surface processing method, laser marking technology has been widely used in fields such as metal processing, electronic manufacturing, automotive parts traceability, anti-counterfeiting markings, and biomedical packaging. Laser marking has the advantages of fast processing speed, clear graphics, and wide applicability of materials. It can achieve local melting, gasification, or color change on the surface of different materials by controlling the wavelength, power, frequency, and pulse parameters of the laser, so as to form permanent text, patterns, code systems, and other marking contents.

[0003] Currently, the most widely used laser marking devices mainly include solid laser marking machines (such as Nd:YAG lasers outputting a wavelength of 1064 nm), fiber laser marking machines, ultraviolet laser marking machines (wavelength of 355 nm), and green laser marking machines (wavelength of 532 nm). Among them, 1064 nm near-infrared laser has become the mainstream technical means for metal marking due to its high absorption efficiency and deep etching ability in metal materials; while 532 nm green laser is widely used in the fine marking of materials such as PCB, ceramics, plastics, and glass due to its high photon energy and better absorption ability on non-metal surfaces. However, due to the significant differences in the response mechanisms of different materials to lasers with different wavelengths, it is difficult for a single-wavelength laser device to simultaneously take into account absorption efficiency, etching quality, and thermal impact control when marking on complex material environments or composite material surfaces, and there are certain limitations.

[0004] Generally speaking, the existing technologies still have the following prominent problems in realizing adaptive laser marking for multiple materials: First, there is a lack of a refined mapping mechanism between the laser wavelength and the material response mechanism. The absorption mechanism of different materials to laser wavelengths is greatly affected by chemical composition, surface structure, and treatment status, and most systems still rely on static databases or empirical rules to match wavelengths, unable to effectively respond to changes in the actual workpiece surface state. Second, the power and pulse combination lack dynamic generation and scheduling capabilities. Single-wavelength laser devices are only optimized for one type of material, with fixed parameter configurations. When facing composite or irregular materials, the power output and pulse behavior do not have dynamic adjustment capabilities, making it difficult to achieve optimal energy transfer. Summary of the Invention

[0005] The main object of the present invention is to provide a high-speed precision marking device based on a dual-wavelength laser system. By setting a projection control unit, automatic identification of the target surface material and wavelength priority sorting are realized. Combining with a wavelength adaptation mapping unit, a mapping table of multi-level power and pulse parameters is constructed for different materials, and the marking control unit is used to dynamically schedule the alternating output of the dual-wavelength laser according to the path segment, so that the system can achieve high-adaptability and high-resolution precision marking for various materials such as metals, ceramics, and plastics. At the same time, a confocal imaging and edge filling mechanism is introduced to effectively improve the clarity of the marking boundary and the overall consistency, and significantly enhance the processing quality and processing efficiency of the system under complex working conditions of multiple materials.

[0006] To solve the above technical problems, the present invention provides a high-speed precision marking device based on a dual-wavelength laser system, which includes: a projection control unit, a wavelength adaptation mapping unit, and a marking control unit; the projection control unit is used to project multi-band detection light onto the area to be marked on the target surface, classify the material of the target surface through synchronous acquisition of the reflection spectrum and the scattering image, and generate a wavelength priority queue corresponding to the material type; the wavelength adaptation mapping unit is used to call a multi-material database in the controller according to the wavelength priority queue, construct a mapping table of multi-level power-pulse combinations of the first wavelength and the second wavelength, and generate an independent energy scheduling curve for each material; the marking control unit is used to convert the graphics to be engraved into a continuous vector instruction stream, combine with the recognized material thermal diffusion coefficient, calculate the pre-offset amount in the laser traveling direction in real time, and complete rasterization and seamless splicing of curve segments; alternately trigger the first wavelength laser and the second wavelength laser within a single marking cycle according to the multi-level power-pulse combination mapping table, and use dual-cavity synchronous threshold control to make the first wavelength laser and the second wavelength laser act on the same marking trajectory in a cross time sequence in the common optical path of the scanning head.

[0007] Furthermore, it further includes: a post-processing unit, which is used to, after the main marking is completed, re-scan the micro-area of the engraved groove with a low-energy long pulse of the second wavelength laser to remove slag and melt micro-burrs to achieve texture smoothing; obtain the marking contour through confocal imaging, perform pixel-level comparison with the continuous vector instruction stream, and re-call the first wavelength laser to perform local filling for the area with deviation exceeding the limit, and finally output a qualified marking result.

[0008] Furthermore, during the marking process, the marking control unit monitors the intensity of the plasma glow by an internal photodetector, and modifies the alternating time sequence and pulse duty cycle in real time through closed-loop control to keep the etching depth of each material surface consistent.

[0009] Further, during the marking process, the marking control unit sets the spot overlap ratio on each marking trajectory. Through the coordinated scheduling of the overlap ratio and the cross-timing, the phenomenon of spot misalignment caused by different wavelengths is suppressed, and the integration time window of the glow intensity is segmented and weighted to achieve rapid compensation for the instantaneous thermochromic effect of different materials.

[0010] Further, when the post-processing unit scans the grooved micro-region again with a low-energy long pulse of the second-wavelength laser, a micro-mist cooling gas is sprayed simultaneously to reduce color drift caused by heat accumulation and improve the surface finish.

[0011] Further, the wavelength range of the first-wavelength laser is in the near-infrared band; the wavelength range of the second-wavelength laser is in the visible light band; the first-wavelength laser and the second-wavelength laser are coupled into the common galvanometer channel through a coaxial beam combiner, and the wavelength switching command is completed by the real-time operating system with no less than two interchanges within one marking cycle.

[0012] Further, after the post-processing unit obtains the marking profile through confocal imaging, it performs pixel-level edge filtering to identify the notch area containing the acute vertex, and limits the local re-etching path to only cover the inner side of the notch area boundary to avoid secondary thermal effects on the qualified area.

[0013] Further, the process of the wavelength adaptation mapping unit constructing the multi-level power-pulse combination mapping table between the first wavelength and the second wavelength includes: reading the wavelength priority queue sorted by absorption efficiency; then calling the absorption threshold, thermal diffusivity, surface roughness, and reflectance entries stored in the multi-material database for each material to be processed, and determining the minimum starting power and safety upper limit power corresponding to the first wavelength and the second wavelength respectively by means of the one-by-one comparison rule; then establishing a multi-level power gradient in the first-wavelength channel in an equally spaced increasing manner, and matching each power gradient with a pulse width and an intermittent window adapted to its heat load to form an initial power-pulse sub-table of the first wavelength; synchronously constructing a corresponding multi-level power-pulse sub-table in the second-wavelength channel according to the reflectance weight of the material; then interleaving and merging the two groups of initial power-pulse sub-tables in the order of the scanning path segments to generate a multi-level power-pulse combination mapping table with dual-wavelength linkage, and inserting three types of labels, namely the preheating section, the constant section, and the ending section, during the merging process to identify the power transition stage; then generating an independent energy scheduling curve containing a power-up buffer section, a steady-state processing section, and a power-down heat suppression section for the material through the time series expansion algorithm according to the multi-level power-pulse combination mapping table; finally writing the energy scheduling curve into the cache area and binding the material identification code for subsequent calling according to the material during the real-time scanning process, thus completing the entire mapping generation process.

[0014] Further, when calling the multi-material database, it also includes: using an embedded reflectivity monitoring probe to instantaneously sample the reflectivity of the target material, and comparing the sampling result with the historical reflectivity average value of this material in the database. When the difference exceeds the set tolerance, the database entry is automatically updated and then the power-pulse sub-table is executed.

[0015] Further, after automatically updating the database entry, a low-power pre-etch test is triggered. A standardized calibration line is marked on the surface of the target material and its etching depth is instantaneously measured. When the measured value is within the preset depth range, it is confirmed that the update is effective; otherwise, the modification is rolled back and two groups of power-pulse sub-tables are recalculated.

[0016] The high-speed precision marking device based on the dual-wavelength laser system of the present invention has the following beneficial effects: Aiming at the differences in laser absorption characteristics of different materials, by introducing a wavelength priority recognition mechanism and a construction method of a multi-level power-pulse mapping table, high-adaptability and high-consistency marking processing control for the surfaces of various materials are realized. The system synchronously collects the reflected spectrum and scattered image of the target area through the projection control unit for material classification, and combines the embedded reflectivity sampling function to dynamically confirm the material state and timely update the database parameters, overcoming the problem of parameter failure of the traditional marking system under inconsistent material batches, surface contamination or film covering conditions. During the marking process, the system constructs a mapping table of the combination of dual-wavelength multi-level power and pulse width based on the material absorption threshold, thermal diffusivity and surface reflectivity through the wavelength adaptation mapping unit, and generates a complete energy curve including power-up, steady-state processing and power-down cooling based on the time-series scheduling strategy, enabling the laser output process to precisely match the material's thermal response window, significantly reducing the diffusion radius of the heat-affected zone and the risk of edge heat accumulation. After the marking is completed, the post-processing unit uses confocal imaging to obtain the marked contour, identifies the notch area through pixel-level edge filtering, and limits the re-etching path to only cover the inside of the defect boundary, thereby realizing high-resolution graphic compensation and avoiding damage to the qualified area caused by repeated heat input. The overall system makes the laser processing path have higher structural closure and graphic continuity under the alternating action of dual wavelengths, and at the same time expands the coverage of dissimilar materials such as metals, ceramics and engineering plastics, and is applicable to manufacturing scenarios with strict requirements for processing accuracy, speed and consistency. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0018] Figure 1Schematic structural diagram of a high-speed precision marking device based on a dual-wavelength laser system provided by an embodiment of the present invention. Detailed implementation manners

[0019] The method of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments of the present invention.

[0020] Example 1, refer to Figure 1 : A high-speed precision marking device based on a dual-wavelength laser system, which includes: a projection control unit, a wavelength adaptation mapping unit, and a marking control unit; the projection control unit is used to project multi-band detection light onto the area to be marked on the target surface, classify the material of the target surface through synchronous acquisition of the reflection spectrum and the scattering image, and generate a wavelength priority queue corresponding to the material type; the wavelength adaptation mapping unit is used to call a multi-material database in the controller according to the wavelength priority queue, construct a multi-level power-pulse combination mapping table of the first wavelength and the second wavelength, and generate an independent energy scheduling curve for each material; the marking control unit is used to convert the graphic to be engraved into a continuous vector instruction stream, combine the recognized material thermal diffusion coefficient, and calculate the pre-offset amount in the laser traveling direction in real time to complete rasterization and seamless splicing of curve segments; alternately trigger the first wavelength laser and the second wavelength laser within a single marking cycle according to the multi-level power-pulse combination mapping table, and use dual-cavity synchronous threshold control to make the first wavelength laser and the second wavelength laser act on the same marking trajectory in a cross time sequence in the common optical path of the scanning head.

[0021] The core function of the projection control unit is to automatically classify the material of the area to be marked on the target surface and generate the basic information for subsequent wavelength adaptation and energy scheduling accordingly. Its specific implementation process starts with the illumination and detection preparation stage of the target surface. In this stage, the illumination module inside the projection control unit will emit detection beams covering multiple wavelength ranges. This multi-band detection light is designed to cover the characteristic absorption spectrum ranges of various materials that may exist on the target surface, so as to ensure the effectiveness and comprehensiveness of subsequent spectral analysis; immediately afterwards, this multi-band detection beam will be projected onto the area to be marked on the target surface at a predetermined illumination angle, and the size and shape of the illumination area need to cover the entire expected marking range to ensure the integrity of material classification; when the detection beam irradiates the target surface, various optical phenomena will occur, including but not limited to reflection and scattering. The key of the projection control unit is to synchronously collect the spectral information reflected back and the image information formed by scattering. To achieve this goal, the unit is equipped with a high-sensitivity spectral acquisition module and an image acquisition module.

[0022] The spectral acquisition module usually adopts a spectrometer or a multi-channel photodetector array, which can decompose the reflected mixed light into its different wavelength components and record the light intensity of each wavelength, so as to obtain the reflection spectral characteristics of the target surface; at the same time, the image acquisition module, such as a CCD or CMOS image sensor, will capture the spatial distribution information of the scattered light on the target surface and form a scattered image containing information such as surface texture and color; after the synchronous acquisition of the reflection spectrum and the scattered image is completed, the data processing module inside the projection control unit will immediately analyze and process the acquired data. For the reflection spectrum data, this module will perform a series of preprocessing steps, such as noise filtering, background correction, and spectral normalization, to improve the quality and comparability of the spectral data. Subsequently, the processed reflection spectrum will be compared and analyzed with the pre-stored material spectral database inside the projection control unit or an accessible external one, which contains the characteristic reflection spectral information of various known materials at different wavelengths. Through algorithms such as pattern recognition and feature matching, the data processing module can identify the specific material type contained in the area to be marked on the target surface. For the scattered image data, the data processing module may perform image enhancement, feature extraction, etc. to assist in the judgment of material classification. Especially when differentiating materials with similar spectra but different surface textures, the scattered image information can provide additional criteria; after successfully identifying the material type of the area to be marked on the target surface, the output module of the projection control unit will generate a wavelength priority queue corresponding to this material type. The core of this queue is to sort according to the absorption characteristics of the identified material for different wavelength lasers. Usually, for a certain specific material, the laser wavelength with the highest absorption efficiency will be given the highest priority because high absorption efficiency means that effective material removal or modification can be achieved with lower energy, thus improving the marking efficiency and reducing the thermal impact on the surrounding area, while the wavelengths with lower absorption efficiency will be given lower priorities.

[0023] The main function of the wavelength adaptation mapping unit is to receive and utilize the wavelength priority queue generated by the projection control unit, and combine it with the pre-stored multi-material database to construct the key parameter mapping relationship and the energy-time-varying scheduling scheme for the subsequent laser marking process. The specific implementation process first receives the wavelength priority queue output from the projection control unit. This queue clarifies the first wavelength and the second wavelength that the system should give priority to considering for the currently identified target surface material, as well as their relative importance. According to this priority order, the wavelength adaptation mapping unit starts the program to call the multi-material database inside its own controller; this multi-material database is a collection of information storing the laser processing characteristics of various materials, and it contains key physical parameters such as the absorption threshold, thermal diffusivity, surface roughness, and reflectivity of each material at different laser wavelengths. The wavelength adaptation mapping unit will retrieve the corresponding parameter entries matching the current target material from this database according to the received material type identification code; after obtaining the relevant parameters of the target material, the core task of the wavelength adaptation mapping unit is to construct a multi-level power-pulse combination mapping table for the first wavelength and the second wavelength. The purpose of this mapping table is to provide a series of alternative laser power and pulse parameter combinations for each material during laser marking to optimize the marking quality and efficiency.

[0024] The construction process first determines the available power range of the first-wavelength laser according to the information such as the absorption threshold and the safety upper limit power retrieved from the database for the first wavelength. Usually, multiple discrete power gradients are established at equal intervals or non-equal intervals between the minimum starting power and the safety upper limit power to form multi-level power; for each determined power gradient, the wavelength adaptation mapping unit will also match the corresponding pulse width and the intermittent window between pulses according to the thermal load at this power level. The pulse width determines the time of a single laser action, while the intermittent window controls the dissipation time of heat between consecutive pulses. By reasonably adjusting the pulse width and the intermittent window, the interaction mode between the laser and the material and the size of the thermal influence area can be controlled, thus forming an initial power-pulse sub-table for the first wavelength; subsequently, the wavelength adaptation mapping unit will synchronously construct the power-pulse sub-table for the second wavelength. This process will also refer to the absorption characteristics of the second wavelength for this material in the database, but may focus more on the reflectivity weight of the material because the second wavelength may be mainly used for auxiliary heating, surface modification, or post-treatment purposes on some materials. Therefore, the settings of its power and pulse parameters may be different from those of the first wavelength; after separately constructing the initial power-pulse sub-tables for the first wavelength and the second wavelength, the wavelength adaptation mapping unit will stagger and merge these two groups of sub-tables according to the order of the expected scanning path segments to generate the final multi-level power-pulse combination mapping table with dual-wavelength linkage.

[0025] During the merging process, in order to achieve smooth power transition and control heat accumulation, the unit will also insert three types of labels, namely preheating section, constant section and ending section, into the mapping table to identify the power parameters to be used at different stages in the marking process. The preheating section usually uses a lower power for preliminary heating of the material; the constant section is the main material removal or modification stage, using a set power-pulse combination; the ending section may reduce the power to reduce thermal stress or optimize surface quality; after constructing the multi-level power-pulse combination mapping table, the wavelength adaptation mapping unit will generate an independent energy scheduling curve for the current material based on the mapping table through a time series expansion algorithm. The curve details when and with what power and pulse parameters the first wavelength laser and the second wavelength laser are triggered during the entire marking process. The energy scheduling curve usually It includes a power increase buffer section, a steady-state processing section and a power reduction heat suppression section. The power increase buffer section is used to slowly increase the laser power to avoid sudden material damage; the steady-state processing section performs the main marking operation according to the parameters in the mapping table; the power reduction heat suppression section gradually reduces the power to reduce thermal effects; finally, the wavelength adaptation mapping unit writes the generated energy scheduling curve into the cache area and binds it to the material identification code previously identified by the projection control unit, so that in the subsequent real-time scanning and marking process, the marking control unit can quickly call the corresponding energy scheduling curve according to the identified material type to achieve optimized marking for different materials. At this point, the wavelength adaptation mapping unit has completed the entire process of calling the multi-material database based on the wavelength priority queue, building a multi-level power-pulse combination mapping table, and generating an independent energy scheduling curve for each material.

[0026] The marking control unit receives the graphic information to be engraved, which is usually input in CAD or other vector graphics formats. The instruction conversion module inside the marking control unit will parse and convert these vector graphics data into a continuous vector instruction stream, which contains the starting point, end point, direction and related attribute information of the basic graphic elements such as straight lines and curves that constitute the marking pattern; after obtaining the vector instruction stream, the marking control unit will retrieve the thermal diffusion coefficient of the material from its internal memory or accessible database in combination with the target material type previously identified by the projection control unit. The thermal diffusion coefficient is an important parameter for measuring the temperature transfer speed inside the material, which directly affects the size and shape of the heat-affected zone when the laser acts on the surface of the material; in order to achieve high-precision marking, especially in the case of high-speed marking, the marking control unit will calculate the pre-offset in the direction of laser travel in real time based on the identified material thermal diffusion coefficient and the preset scanning speed. The purpose of this pre-offset is to compensate for the deformation or dislocation of the mark that may occur due to the thermal effect of the material and the delay of the laser action during high-speed scanning. By introducing the pre-offset in the instruction, the size accuracy and shape accuracy of the final mark can be ensured.

[0027] For complex graphics, especially those containing curved segments, the marking control unit also needs to perform rasterization and seamless splicing of curved segments. Rasterization is the process of converting a vector graphic into a dot matrix pattern composed of a series of discrete points to facilitate the line-by-line scanning and marking of the laser scanning head. The seamless splicing of curved segments ensures that during the rasterization process, the curve can be smoothly approximated to avoid phenomena such as jaggedness or breaks. The marking control unit will adopt specific algorithms, such as the scan line algorithm or the contour tracking algorithm, to convert the continuous vector instruction stream into a discrete sequence of scanning path points. When processing curved segments, by adjusting the distance and direction between adjacent scan lines, smooth connection is achieved. After preparing the sequence of scanning path points, the marking control unit will enter the laser trigger control stage. The core of this stage is to alternately trigger the first-wavelength laser and the second-wavelength laser within each single marking cycle according to the multi-level power-pulse combination mapping table generated by the wavelength adaptation mapping unit before. Here, the single marking cycle refers to the time taken for the laser scanning head to complete a marking trajectory (i.e., a scan line or a curved segment) on the target surface.

[0028] To achieve precise wavelength alternation, the marking control unit utilizes dual-cavity synchronous threshold control technology, which can accurately control the triggering sequence and duration of two independent lasers in time, ensuring that the first-wavelength laser and the second-wavelength laser act on the same marking trajectory on the target surface in the common optical path of the scanning head with precise cross-timing. The specific arrangement of the cross-timing, such as the duration of each wavelength, the alternation frequency, etc., will be determined according to the preset parameters in the multi-level power-pulse combination mapping table; during the actual marking process, to further optimize the marking quality, the marking control unit will also use the built-in photodetector to continuously monitor the intensity of the plasma glow generated in the laser action area. The intensity of the plasma glow is closely related to the etching depth and material removal efficiency of the laser. The marking control unit compares the monitored glow intensity with the preset target value through a closed-loop control system and modifies the cross-timing and pulse duty cycle of the alternating trigger in real time according to the comparison result to maintain a consistent etching depth on different material surfaces or different regions of the same material; in addition, to suppress the spot misalignment phenomenon that may be caused by the action of lasers with different wavelengths, the marking control unit will set an appropriate spot overlap ratio on each marking trajectory and ensure reasonable overlap between adjacent laser spots and between laser spots with different wavelengths through the coordinated scheduling of the overlap ratio and cross-timing, thereby improving the uniformity and continuity of the marking; for the instantaneous thermochromic effect that different materials may exhibit, the marking control unit will also perform segmented weighted processing on the integration time window of the monitored glow intensity, which means that different weights will be assigned to the data in different time periods when analyzing the glow intensity to more quickly respond to and compensate for the color changes of different materials under laser action; finally, the marking control unit sends the generated control signal to the laser and the scanning head, driving the laser beam to perform high-speed and precise marking on the target surface according to the predetermined path and energy parameters, completing the process of converting the graphics to be engraved into actual marks..

[0029] Furthermore, it also includes: a post-processing unit, which is used to re-scan the micro-region of the groove with a low-energy long pulse of the second-wavelength laser after the main marking is completed, remove the slag and melt the micro-burrs to achieve smooth texture; obtain the marking contour through confocal imaging, perform pixel-level comparison with the continuous vector instruction stream, and re-call the first-wavelength laser to perform local supplementary engraving on the area where the deviation exceeds the limit, and finally output a qualified marking result.

[0030] The high-speed precision marking device based on the dual-wavelength laser system also includes a post-processing unit. Its function is to further optimize and conduct quality inspection on the marked area after the main marking task executed by the marking control unit, so as to ensure that the final marking result meets the predetermined standards. The post-processing unit first activates the second-wavelength laser for the micro-region of the groove after marking and sets it to the working mode of low energy and long pulse. Then it scans this area again. The purpose of this scan is to utilize the interaction characteristics between the second-wavelength laser and the material to effectively remove the slag and fine surface protrusions, namely micro-burrs, that may be generated during the main marking process. The low-energy long pulse enables the second-wavelength laser to slightly input energy to the edge and bottom of the groove without significantly changing the original marking shape and depth, making the remaining molten material remelt and flow, thereby filling the tiny gaps and reducing the surface roughness to achieve the smoothing of the marking texture. This step is crucial for improving the aesthetics and functionality of the marking, especially in applications with high requirements for surface finish.

[0031] After completing the surface smoothing process, the post-processing unit will activate its quality detection and correction function. This function first conducts high-precision three-dimensional scanning imaging of the marked contour through the integrated confocal imaging system. The confocal imaging technology can provide spatial resolution at the micron or even nanometer level, thereby accurately obtaining information such as the actual shape, size, and depth of the marking. The post-processing unit converts the marked contour data collected by the confocal imaging system into pixel-level image information, and then makes a pixel-by-pixel comparison with the continuous vector instruction stream initially generated by the instruction conversion module. Here, the continuous vector instruction stream represents the ideal marking pattern. By comparing the differences between the actual marking image and the ideal marking pattern, the post-processing unit can accurately identify the deviations existing in the marking, such as defects like size deviation, shape distortion, edge irregularity, or local missing.

[0032] The system will preset a deviation tolerance range in advance. When the deviation between the actual mark and the ideal mark exceeds this tolerance, this area will be determined as a non-conforming area; once an area with an excessive deviation is identified, the post-processing unit will reactivate the first-wavelength laser and perform a local re-etching operation on these specific non-conforming areas. The purpose of re-etching is to correct the errors that occurred during the previous marking process and make it as close as possible or even fully meet the requirements of the original vector instructions. Precise control of local re-etching is crucial. The post-processing unit will accurately adjust the power, pulse parameters, and scanning trajectory of the first-wavelength laser according to the type and degree of deviation, ensuring that the re-etching operation is only carried out in the areas that need to be corrected and avoiding secondary impacts on the already qualified areas, thereby guaranteeing the accuracy and quality of the overall mark; after completing the local re-etching of all areas with excessive deviations, the post-processing unit will use the confocal imaging system to re-inspect the entire mark again to confirm that all deviations have been effectively corrected. If the re-inspection result shows that the mark already meets the predetermined quality standard, then the post-processing unit will output the final qualified marking result, which can be presented in the form of a visual signal, an electrical signal, or a data file, indicating that the mark on the target surface has been completed and the quality is qualified; if the re-inspection still finds that there are excessive deviations, the post-processing unit may, according to the set process, perform the smoothing process of the second wavelength and the local re-etching of the first wavelength again until the mark quality meets the requirements or reaches the set maximum number of iterations. Through the above steps, the post-processing unit effectively improves the overall performance of the high-speed precision marking equipment based on the dual-wavelength laser system, not only achieving high-quality surface marking but also possessing the capabilities of automated quality inspection and defect repair, ultimately ensuring that each output marking result is qualified.

[0033] Furthermore, during the marking process, the marking control unit monitors the intensity of plasma glow by an in-built photodetector and modifies the alternating time sequence and pulse duty cycle in real time through closed-loop control to keep the etching depth consistent on the surfaces of various materials.

[0034] The marking control unit integrates a built-in photodetector to ensure consistent etching depth on different material surfaces. The main function of this photodetector is to continuously monitor the intensity of the plasma glow generated when the laser interacts with the material. Plasma glow is the luminous phenomenon of the high-temperature plasma generated when the laser ablates the material, and there is a direct correlation between its intensity and the laser energy density, the material absorption rate, and the actual etching depth. The marking control unit continuously collects the intensity data of the plasma glow through this built-in photodetector and inputs these real-time data into a closed-loop control system. The core of this closed-loop control system is to compare the actually monitored glow intensity with a pre-set target glow intensity value. The target glow intensity value is determined based on the characteristics of the target material and the desired etching depth, and can be obtained from a multi-material database or pre-set by the user. If there is a deviation between the actually monitored plasma glow intensity and the target value, it indicates that the current etching depth may deviate from the expected value, possibly being too deep or too shallow.

[0035] The closed-loop control system of the marking control unit will adjust the alternating timing and pulse duty cycle of the laser in real time according to the magnitude and direction of the deviation. The alternating timing refers to the time interval and sequence of switching between the first-wavelength laser and the second-wavelength laser, while the pulse duty cycle is the ratio of the duration of the laser pulse to the total time within a pulse period. By adjusting these two parameters, the marking control unit can effectively control the laser energy acting on the material surface per unit time, thereby affecting the material removal rate and the final etching depth. For example, if the monitored glow intensity is lower than the target value, indicating that the etching depth may be insufficient, the control system may adjust to increase the pulse duty cycle of the first-wavelength laser, extend its action time, or adjust the alternating timing to increase the triggering frequency of the first-wavelength laser to increase the energy input. Conversely, if the glow intensity is higher than the target value, indicating that the etching may be too deep, the control system will take opposite measures, such as reducing the pulse duty cycle or adjusting the alternating timing to reduce the energy input. This real-time closed-loop control mechanism can dynamically adapt to the reaction differences of different materials under laser action, compensate for the etching depth fluctuations caused by the unevenness of the material's own characteristics or environmental factor changes, so as to ensure consistent and accurate etching depth on various material surfaces, ultimately improving the quality and reliability of marking. The marking control unit monitors the glow intensity and adjusts the parameters at a certain frequency. This frequency needs to be high enough to be able to respond promptly to the changes during the etching process, but also avoid overly frequent adjustments that may cause system instability. The closed-loop control algorithm usually adopts PID control or other adaptive control strategies to achieve fast, stable, and precise etching depth control.

[0036] Furthermore, during the marking process, the marking control unit sets the laser spot overlap ratio on each marking trajectory. Through the coordinated scheduling of the overlap ratio and the cross timing, the phenomenon of spot misalignment caused by different wavelengths is suppressed, and the integration time window of the glow intensity is segmented and weighted to achieve rapid compensation for the instantaneous thermochromic effect of different materials.

[0037] In order to further improve the marking quality and accuracy, the marking control unit pre-sets a suitable laser spot overlap ratio on each marking trajectory. The laser spot overlap ratio refers to the size ratio of the overlapping area between adjacent two laser spots during the laser scanning process. Appropriate overlap can ensure the continuity and uniformity of the marking, and avoid defects such as discontinuity or missed marking. For a dual-wavelength laser system, since the first-wavelength laser and the second-wavelength laser may have different spot sizes and action characteristics, if not controlled, spot misalignment may occur during the alternating action on the same marking trajectory, resulting in blurred marking edges or unexpected visual effects. Therefore, the marking control unit realizes the coordinated scheduling of the laser spot overlap ratio and the cross timing by precisely controlling the trigger timing of the laser and the moving speed of the scanning head, so that the spots formed by the action of different-wavelength lasers can be optimized in space and time, effectively suppressing the spot misalignment phenomenon and ensuring the clarity and sharpness of the marking.

[0038] In addition, for the instantaneous thermochromic effect that may occur in different materials under laser irradiation, the marking control unit also adopts the technology of segmentally weighting the integration time window of the plasma glow intensity. As mentioned above, the glow intensity is an important indicator reflecting the etching state. However, in some materials, the local instantaneous heating caused by laser irradiation may cause the surface color of the material to change rapidly. Although this change is a manifestation of the thermal effect, if the average glow intensity within the overall integration time window is directly used for control, the color control may be inaccurate due to insufficient response speed. To solve this problem, the marking control unit divides the monitored plasma glow signal into several time periods within an integration time window and assigns different weight coefficients to different time periods. Usually, the time period closer to the current moment is assigned a higher weight, so that the control system can more sensitively capture the instantaneous change in the glow intensity and respond more quickly to the color deviation caused by the thermochromic effect. Through this segmentally weighted integration method, the marking control unit can more quickly adjust parameters such as the alternating timing and pulse duty cycle of the laser, thereby achieving rapid compensation for the instantaneous thermochromic effect of different materials, maintaining the consistency and stability of the marking color, and finally obtaining a higher-quality marking effect.

[0039] Furthermore, when the post-processing unit re-scans the grooved micro-area with a low-energy long pulse of a second wavelength laser, micro-mist cooling gas is simultaneously sprayed to reduce color drift caused by heat accumulation and improve surface finish.

[0040] These cooling gases are usually precisely controlled in flow and pressure to ensure uniformity and appropriateness of the cooling effect; the ejected micro-mist cooling gas contacts the surface of the material heated by the laser, and uses the gas's latent heat of evaporation to quickly remove the heat from the surface of the material, thereby effectively reducing the temperature of the local area. This timely heat dissipation helps prevent the continued accumulation of heat inside the material, and excessive heat accumulation is one of the main causes of color drift. Especially when making precision markings on color-sensitive materials, controlling heat accumulation is crucial to obtaining accurate and consistent color markings; in addition, the injection of micro-mist cooling gas can also remove tiny debris and contaminants generated during laser ablation to a certain extent, further improving the cleanliness and surface finish of the marking area. While reducing the surface temperature, the cooling gas also slows down the cooling rate of the molten material, allowing it to have more time to flow and spread under the action of surface tension, thereby forming a smoother surface and reducing microscopic roughness. The nozzle of the micro-mist cooling gas injection system is usually designed to accurately guide the cooling gas to the action area of the second wavelength laser to ensure the maximization of the cooling effect and the optimization of the efficiency. The type of cooling gas can be selected according to the characteristics of the target material. For example, clean air, nitrogen or other inert gases can be used to avoid undesirable chemical reactions with the material. Through the low-energy long-pulse scanning of the second wavelength laser and the synchronous action of the micro-mist cooling gas, the post-processing unit can significantly improve the quality of the mark, not only removing slag and molten micro-burrs to achieve smooth texture, but also effectively suppressing the color drift caused by heat accumulation, and finally obtaining a precision marking result with higher surface finish and more stable color.

[0041] Furthermore, the wavelength range of the first wavelength laser is in the near-infrared band; the wavelength range of the second wavelength laser is in the visible light band; the first wavelength laser and the second wavelength laser are coupled into a common galvanometer channel through a coaxial beam combiner, and the wavelength switching instruction is exchanged by the real-time operating system at least twice within a marking cycle.

[0042] The laser wavelength range emitted by the first-wavelength laser is set in the near-infrared band. Lasers in the near-infrared band usually have high power output and good material versatility, can be effectively absorbed by a variety of materials and achieve rapid material removal or modification, so it is selected as the main marking light source; while the laser wavelength range emitted by the second-wavelength laser is in the visible light band. Lasers in the visible light band, especially visible light lasers with specific wavelengths, such as green or blue lasers, may have higher absorption rates on certain specific materials, or are more suitable for applications such as fine marking, surface modification or color marking, so they are used as the light source for auxiliary marking or post-processing. In order to enable these two lasers with different wavelengths to share a set of scanning galvanometer systems, thereby simplifying the optical path structure and improving the compactness of the system, the present invention uses a coaxial beam combiner to couple the first-wavelength laser and the second-wavelength laser into the same shared galvanometer channel. The coaxial beam combiner is a special optical element, whose design allows specific wavelength beams to transmit through, while other specific wavelength beams are reflected. By selecting a coaxial beam combiner with appropriate spectral characteristics, the near-infrared laser and the visible light laser can be precisely superimposed in space to form a coaxial composite beam. This composite beam then enters the galvanometer system, and the galvanometer controls its scanning on the target surface. In order to achieve fast switching and precise control of the dual-wavelength laser during the marking process, the marking control unit of the system is equipped with a real-time operating system, which can complete the interchange of wavelength switching instructions no less than twice within a marking cycle. A marking cycle usually refers to the time taken for the laser scanning head to complete a minimum marking unit (such as a pixel or a small section on a scan line) on the target surface. Achieving two or more wavelength switches in such a short time means that the system can quickly switch between the first-wavelength laser and the second-wavelength laser according to needs in a very short time, thereby realizing complex dual-wavelength collaborative marking strategies, such as using different wavelengths in different parts of the same marking trajectory, or continuously irradiating the same position with lasers of two wavelengths at very short time intervals. This high-speed wavelength switching ability provides an important technical basis for achieving high-quality, high-efficiency and multi-functional precision laser marking.

[0043] Further, after the post-processing unit obtains the marking profile through confocal imaging, it performs pixel-level edge filtering to identify the notch area containing acute-angled vertices, and defines that the local re-engraving path only covers the inner side of the boundary of the notch area to avoid causing secondary thermal effects on the qualified area.

[0044] In the high-speed precision marking equipment based on the dual-wavelength laser system of the present invention, the post-processing unit undertakes key quality correction and surface optimization tasks in the entire marking process. Especially in high-precision marking applications, it is of great significance for eliminating edge notches caused by local thermal inhomogeneity of materials, spot distortion, or path perturbation. This unit immediately activates the confocal imaging module after the main laser marking process to perform a high-resolution contour scan of the marked area. The confocal imaging system obtains a three-dimensional contour image of the target marked area through precise focusing and layer-by-layer reflection intensity scanning. Its image data reflects the geometric consistency between the actual etching path and the designed pattern with pixel-level accuracy. During the imaging process, the reflection response of the scanning spot at each pixel position is recorded in real time, converted into a digital signal by a high-sensitivity photoelectric conversion module, and then a clear and distinguishable marked contour map is generated through an image reconstruction processing algorithm.

[0045] After completing the construction of the contour image, the post-processing unit enters the pixel-level edge analysis process. The system calls an internal edge recognition algorithm to perform continuity detection on the areas with sudden changes in brightness gradient in the image, identifies the turning points of the curve by detecting the change rate of the boundary direction, and then extracts all boundary line segments and automatically separates the local areas containing acute-angled vertices. This process is particularly important for identifying notches caused by laser power overshoot during high-speed scanning turning, mechanical response delay of the scanning head, or dual-wavelength energy coupling error. The identified acute-angled vertices usually correspond to the weakest positions on the graphic edge. The system preferentially determines whether there are phenomena such as insufficient marking depth, blurred boundary contour, or line width contraction in these areas during the analysis process.

[0046] After the recognition process is completed, the system aligns the notched area with the original designed pattern at the pixel level and generates a marking defect mask through a difference image. This mask defines the spatial range of the laser trajectory during the subsequent repair engraving process, and only allows the repair engraving operation to be performed inside the boundary covered by the defect mask. The generation of the specific repair engraving path is based on the local fitting of the original vector path while avoiding qualified areas to ensure that the laser repair engraving energy will not spread beyond the qualified engraved lines, thereby avoiding the damage of secondary thermal influence to the edge finish and structural accuracy.

[0047] The repair engraving operation adopts the low-power mode of the second-wavelength laser source and is combined with shortening the pulse width to reduce the heat input. At the same time, it uses its strong surface absorption ability to slightly etch the notched area. The system keeps the confocal imaging turned on in real time during the repair engraving process, dynamically monitors the area after each repair engraving. When the matching error between the contour reconstruction image and the design path drops below the set threshold, the system automatically terminates the repair engraving task and enters the subsequent processing flow. Through the above repair engraving control mechanism, this post-processing unit effectively improves the consistency and integrity of the marking edge, reduces the risk of edge distortion common in high-precision marking, ensures the geometric accuracy and appearance quality of the overall pattern, and is an indispensable component module for realizing multi-material high-precision marking.

[0048] Further, the process of the wavelength adaptation mapping unit constructing the multi-level power-pulse combination mapping table of the first wavelength and the second wavelength includes: reading the wavelength priority queue sorted by absorption efficiency; then calling the absorption threshold, thermal diffusivity, surface roughness, and reflectivity entries stored in the multi-material database for each material to be processed, and determining the minimum starting power and safety upper limit power corresponding to the first wavelength and the second wavelength respectively by means of the one-by-one comparison rule; then establishing a multi-level power gradient in the first wavelength channel in an equally spaced increasing manner, and matching each power gradient with a pulse width and an intermittent window adapted to its heat load to form the initial power-pulse sub-table of the first wavelength; simultaneously constructing the corresponding multi-level power-pulse sub-table in the second wavelength channel according to the reflectivity weight of the material; then interleaving and merging the two groups of initial power-pulse sub-tables in the order of the scanning path segments to generate a multi-level power-pulse combination mapping table with dual-wavelength linkage, and inserting three types of labels, namely the preheating section, the constant section, and the ending section, during the merging process to identify the power transition stage; then generating an independent energy scheduling curve including a power-up buffer section, a steady-state processing section, and a power-down heat suppression section for the material through the time series expansion algorithm according to the multi-level power-pulse combination mapping table; finally, writing the energy scheduling curve into the cache area and binding the material identification code for subsequent calling according to the material during the real-time scanning process, thus completing the entire mapping generation process.

[0049] First, after the marking device completes the material identification on the surface of the target workpiece, the identification result will be transmitted to the wavelength adaptation mapping unit in the form of a wavelength priority queue. The information recorded in this queue is arranged in descending order of the absorption efficiency of the current material for the two laser wavelengths, and is used to indicate which wavelength should be the main processing carrier in the subsequent marking process. The establishment of the wavelength priority is based on the accurate comparison of the multi-band spectral analysis completed by the front-end projection control unit and the characteristic entries of the material database, and has high consistency and credibility.

[0050] After receiving the wavelength priority instruction, the wavelength adaptation and mapping unit first calls the multi-material database stored locally inside. In this database, multiple physical parameter entries are saved for each recognizable material, including but not limited to the laser absorption threshold, thermal diffusivity, surface roughness grade, and reflectivity corresponding to different wavelengths. The system retrieves the corresponding entries according to the current material identification code and sequentially reads the parameter sets related to the first wavelength and the second wavelength in the order of wavelength priority. During this process, the system uses a set of preset one-by-one comparison rules to first determine the available power range of each wavelength on this material. This comparison rule comprehensively considers the minimum excitation response of the material, the allowable thermal accumulation threshold, and the tolerance to the thermal gradient, so as to respectively determine the minimum starting power and the safety upper limit power corresponding to the first wavelength and the second wavelength.

[0051] After completing the establishment of the preliminary power range, the system independently constructs its own power-pulse sub-tables in the first wavelength channel and the second wavelength channel respectively. In the first wavelength channel, the system establishes a multi-level power gradient with a preset equally spaced increasing strategy, and each level of power is regarded as the representative of an independent marking mode. For each level of power, the system will match a pulse width and its intermittent window combination that is thermally load-adapted according to the thermal influence range, ablation rate, and edge expansion trend that the power level may cause in the target material. This matching operation depends on the prediction result of the internal coupling model for the thermal-mechanical response relationship between the laser pulse and the material, ensuring that each set of parameter combinations has a stable processing output effect. At the same time, in the second wavelength channel, the system redistributes the power gradient according to the reflectivity weight of the material. On the surface of materials with a higher reflectivity, the system automatically lowers the starting power threshold to avoid laser dissipation and safety risks caused by high reflectivity; on materials with a lower reflectivity, the system appropriately increases the power configuration in the middle and high levels, thereby optimizing the energy absorption efficiency of the material. On this basis, a multi-level power-pulse combination is also established to form the initial power-pulse sub-table of the second wavelength channel.

[0052] After the generation of the above two groups of sub-tables is completed, the wavelength adaptation mapping unit enters the interleaved merging stage. The system divides the scanning trajectory into multiple continuous paragraphs according to the vector path segment information generated by the current pattern to be marked, and inserts the power-pulse combination items of the first wavelength and the second wavelength into each paragraph in the order of the path segment numbers. This process follows the principle of primary and secondary wavelength rotation, that is, the laser wavelength with a higher ranking in the wavelength priority is preferentially used to process the main path, while the other wavelength is interspersed for the auxiliary path or the boundary modification area. To ensure the stability of energy transfer during the switching of the two wavelengths, the system inserts three stage tags in the merged path, namely the preheating section, the constant section, and the ending section. The preheating section is usually set at the start of the path and uses a low-power combination to activate the surface response; the constant section is in the middle section and uses medium and high power parameters to achieve the main marking; the ending section is at the end of the path and is used for thermal buffering and edge convergence processing. These tags not only indicate the scheduling pattern of the laser power curve but also play a role in time synchronization and laser cavity pressure control cooperation in subsequent energy scheduling.

[0053] After the construction of the mapping table is completed, the system generates a complete energy scheduling curve for the material through a time series expansion algorithm based on the synthesized dual-wavelength multi-level power-pulse mapping table. This curve includes three structural sub-sections: the power-up buffer section, the steady-state processing section, and the power-down heat suppression section. Pulse duration, wavelength channel switching points, and safety intermittent windows are respectively set for each curve section, so that the scheduling curve can not only accurately control the local heat input of the laser on the material surface but also be precisely aligned with the scanning head motion instructions during the operation of the system. After the curve generation is completed, the system writes it into the cache area and binds the material identification code generated by the material identification module before, so as to ensure that the subsequent scanning control unit can quickly load and apply the corresponding scheduling curve according to the identification result during the actual marking process, without having to re-call the database or re-calculate the energy path, thus greatly improving the system processing efficiency and parallel processing ability.

[0054] Furthermore, when calling the multi-material database, it also includes: using an embedded reflectivity monitoring probe to perform instant reflectivity sampling on the target material, and comparing the sampling result with the historical reflectivity mean value of this material in the database. When the difference exceeds the set tolerance, the database entry is automatically updated and then the power-pulse sub-table is executed.

[0055] After the device completes the positioning and material identification of the target workpiece, the embedded reflectivity monitoring probe is activated. Through a dedicated optical fiber coupling path, the probe projects a highly stable and low-power test beam vertically onto the center point or representative area of the area to be marked. After the beam is incident on the target surface, the reflected light will show intensity changes due to factors such as material type, surface condition, and pre-processing technology before processing. The reflected light signal is collected by the receiving module of the reflectivity probe and converted into digital reflectivity data through an internal optoelectronic conversion system. The sampling process has high time resolution and strong signal-to-noise ratio suppression ability, can complete high-precision collection in an extremely short time, and does not interfere with the subsequent laser processing process.

[0056] After completing the reflectivity sampling, the system compares and analyzes the current instantaneous reflectivity data with the historical reflectivity mean stored in the database. This historical data is accumulated based on large-sample process tests in the early stage and has a certain statistical weight and representativeness. During the comparison process, the system sets a group of material-specific tolerance thresholds, which take into account both the reasonable fluctuation range of the natural properties of the material and exclude occasional abnormal data caused by external environmental disturbances. When the comparison result shows that the current reflectivity sampling value is within the tolerance range of the historical data, the system considers that the database entry is still available, makes no adjustment, and continues to generate the power-pulse sub-table according to the original parameters; if the comparison result shows that the deviation between the current reflectivity and the historical mean exceeds the tolerance range, the system will automatically enter the database update process.

[0057] In the database update process, the system first locks the parameter entry corresponding to the current material identification code and calls the reflectivity correction function to rewrite the reflection-related parameters in real time. The corrected parameters include not only the average reflectivity value but also affect multiple key dimensions such as the determination of the thermal input threshold, the setting of the starting power level, and the calculation of the pulse modulation window length for this material under different wavelength conditions. After completing the data update, the system reconstructs the corresponding first-wavelength and second-wavelength power-pulse sub-tables for this material and reorganizes the power gradient and pulse width mapping logic according to the latest parameters to ensure the optimal matching state between the laser output characteristics and the material response.

[0058] Furthermore, after automatically updating the database entry, a low-power pre-etch test is triggered. A standardized calibration line is marked on the surface of the target material and its etching depth is measured immediately. The update is confirmed to be effective only when the measured value is within the preset depth range; otherwise, the modification is rolled back and two groups of power-pulse sub-tables are recalculated.

[0059] After the deviation between the reflectivity sampling result and the historical mean exceeds the tolerance range and the database entry update is completed, the system immediately starts a low-power pre-etch test program on the surface of the target material. This program controls the laser output unit to load a specific test mode, which uses the power-pulse combination with the lowest energy level in the currently updated parameter combination for laser emission, and scribes a standardized calibration line on the workpiece surface according to a predefined path. The geometric form, length, and scribing direction of this calibration line are all fixed configurations, aiming to eliminate the interference of path factors on the etching result and also facilitate the rapid identification and analysis of the subsequent optical measurement system.

[0060] After scribing is completed, the system immediately calls the online confocal measurement module to perform real-time detection of the etching depth of the calibration line. This module uses a high-precision Z-axis response platform in cooperation with a multi-focus imaging structure to obtain the depth profile data of the area where the calibration line is located in a very short time. The obtained etching depth value will be compared with the reference depth range preset inside the system. This reference range is based on the theoretical expected value derived from the thermal response characteristics of the target material, the spot diameter, and the laser power setting, and combines a certain process tolerance interval. During the comparison process, the system not only detects whether the average etching depth falls within the set range but also evaluates the depth uniformity and edge integrity to determine whether the laser has good process adaptability under this parameter configuration.

[0061] When the measurement result shows that the etching depth is within the preset range, the system will confirm that the updated database parameters are feasible for processing and generate the corresponding power-pulse sub-table based on this for subsequent actual marking tasks. If the measurement result shows that the etching depth significantly deviates from the set range, the system will determine that the updated reflectivity parameters do not meet the theoretical expectation at the processing level and immediately execute a rollback operation. The rollback mechanism restores all the updated parameters in the database to their states before the update and triggers a recalculation process to reconstruct two groups of power-pulse sub-tables for the first wavelength and the second wavelength based on the historical parameters again.

[0062] This embodiment relates to a process of performing high-precision two-dimensional coding graphic marking on the surface of 6061-T6 aluminum alloy material. The surface of the selected material is anodized, with medium reflectivity and strong heat diffusion performance. The target is to mark a DataMatrix coding graphic with a size of 5mm×5mm on the material surface area, which contains 48 coding units in total. It is required that the width of a single dot matrix is less than 0.08mm, the etching depth is controlled within 25±5 microns, the graphic edge should have high clarity, no redundant heat-affected area, and the overall marking time should be controlled within 2 seconds.

[0063] First, the projection control unit identifies the optical properties of the material in the target area. The collected reflection spectrum data shows that the reflectivity of this anodized aluminum alloy for a laser with a wavelength of 1064 nm is approximately 87%, and for a laser with a wavelength of 532 nm is approximately 46%. The system calls the optical parameters of 6061 aluminum alloy already existing in the database and obtains its historical average reflectivity: 85% corresponding to 1064 nm and 45% corresponding to 532 nm. According to the tolerance threshold of ±5% preset by the system, the deviations of the two groups of data are 2% and 1% respectively, both within the set range. Therefore, the system determines that there is no need to update the database entry. Further, according to the absorption efficiency ranking, the system determines that the wavelength priority is 532 nm first and 1064 nm as auxiliary.

[0064] Next, the system calls the thermophysical property data of this material in the database, including key entries such as the laser absorption threshold, thermal diffusivity, and surface roughness. The absorption threshold of 6061 anodized aluminum under the action of a 532 nm laser is 0.65 J / cm 2 , and under the action of a 1064 nm laser is 1.25 J / cm 2 , and the thermal diffusivity is α = 8.5×10 ―6 m 2 / s. To suppress edge heat expansion, the single-pulse thermal diffusion length L needs to be controlled within 10 microns. According to the thermal diffusion relation formula:

[0065]

[0066] Set the target diffusion length L = 7×10 ―6 m, and substitute it into the calculation of the pulse action time t:

[0067]

[0068] Thus, the pulse width is set to be concentrated between 40 ns and 100 ns. The system configures power gradients and pulse width combinations for the two laser wavelengths respectively. For the 532 nm laser, the power levels are set to 4 W, 6 W, 8 W, 10 W, and 12 W, and the corresponding pulse widths are 40 ns, 60 ns, 80 ns, 100 ns. For the 1064 nm laser, the power levels are set to 6 W, 9 W, 12 W, 15 W, and 18 W, and the pulse widths are 60 ns, 90 ns, and 120 ns. The system matches each power with the pulse width through a calculation model to form two power-pulse sub-tables.

[0069] To establish a marking scheduling path, the system divides the entire scanning process into three segments according to the vector trajectory of the marking pattern: the starting preheating segment (the first 10% of the path), the main processing segment (the middle 80%), and the ending heat suppression segment (the last 10%). In the starting segment, a low-power parameter (4W, 40ns) with a wavelength of 532nm is used to slowly preheat the material surface; in the main segment, two sets of parameters, 532nm@8W@80ns and 1064nm@12W@90ns, are used alternately, and the laser channel switching frequency is set to 45 times per second; in the ending segment, a shallow engraving buffer is performed with the parameter of 1064nm@6W@60ns to prevent heat accumulation.

[0070] Based on the above segmented control strategy, the system constructs a time scheduling curve, arranges the power and pulse combinations along the time axis, and each laser cycle contains a complete structure of a power-up buffer segment, a steady-state processing segment, and a power-down cooling segment. The scanning galvanometer commands and the laser output timing are scheduled through a unified time synchronization module, enabling the alternating output of the dual-wavelength lasers to act on the same graphic trajectory, avoiding the spread of the heat-affected zone and improving the boundary clarity.

[0071] To ensure the implementability of the scheduling parameters, the system starts a pre-engraving test mechanism, engraves a standard line segment with a length of 2mm at the edge of the marking area, uses the parameter of 532nm@8W@80ns, sets the line speed to 100mm / s, and the repetition frequency to 20kHz. After the marking is completed, the system detects the etching depth through a confocal optical measurement module. The measured result is 26 microns, which falls within the target depth range (25±5 microns). The system confirms that this parameter combination is effective and the scheduling curve can be put into use.

[0072] When performing the formal marking task, the system completes the scanning of the entire encoded pattern and schedules the laser sources of the two wavelengths in a timely manner. After the marking is completed, the system calls the post-processing unit again to perform confocal contour imaging on the marked area, and the edge detection module statistically analyzes the boundary clarity and line width of all 48 encoded units. The analysis results show that the line width error is less than 5 microns, there is no secondary overlap at the boundary, all dot matrices are above the recognizable intensity threshold, and the final graphic recognition rate reaches 100%. The entire marking process takes 1.82 seconds in total, the system state is stable, there is no lag phenomenon in the beam energy switching, and the scanning head response control error is controlled within the range of ±3 microns.

[0073] This example proves that the proposed system can achieve high-precision marking of thermosensitive materials in a dual-wavelength laser environment, and has the ability of closed-loop control of material response, adapting to the dynamic adjustment of multi-batch workpieces under the condition of slight parameter differences, especially suitable for the encoding marking operations on aerospace electronic components, micro-molds, and metal packaging components. The whole process reflects the complete chain of the system from material recognition, parameter matching, scheduling execution to quality feedback, which is an important implementation path for the industrial promotion of the present invention.

[0074] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that these specific embodiments are merely illustrative. Without departing from the principles and essence of the present invention, those skilled in the art can make various omissions, substitutions, and changes to the details of the above methods and systems. For example, combining the above method steps so as to perform substantially the same function in a substantially the same way to achieve substantially the same result falls within the scope of the present invention. Therefore, the scope of the present invention is only defined by the appended claims.

Claims

1. A high-speed precision marking device based on a dual-wavelength laser system, characterized in that, It includes: a projection control unit, a wavelength adaptation mapping unit, and a marking control unit; The projection control unit is configured to project multi-band detection light onto the area to be marked on the target surface, classify the material of the target surface through synchronous acquisition of the reflection spectrum and the scattering image, and generate a wavelength priority queue corresponding to the material type; the wavelength adaptation mapping unit is configured to call a multi-material database in the controller according to the wavelength priority queue, construct a multi-level power-pulse combination mapping table between the first wavelength and the second wavelength, and generate an independent energy scheduling curve for each material; The marking control unit is configured to convert the pattern to be engraved into a continuous vector instruction stream, combine the recognized material thermal diffusivity, and calculate the pre-offset amount in the laser traveling direction in real time to complete rasterization and seamless splicing of curve segments; According to the multi-level power-pulse combination mapping table, the first wavelength laser and the second wavelength laser are alternately triggered within a single marking cycle, and the double-chamber synchronous threshold control is used to make the first wavelength laser and the second wavelength laser act on the same marking trajectory in a cross timing manner in the common optical path of the scanning head.

2. The high-speed precision marking device based on a dual-wavelength laser system according to claim 1, characterized in that, It further includes: a post-processing unit, which is configured to, after the main marking is completed, use the low-energy long pulse of the second wavelength laser to scan the micro-region of the engraved groove again to remove slag and melt micro-burrs to achieve texture smoothing; obtain the marking contour through confocal imaging, perform pixel-level comparison with the continuous vector instruction stream, and re-call the first wavelength laser to perform local re-engraving on the area with excessive deviation, and finally output a qualified marking result.

3. The high-speed precision marking device based on the dual-wavelength laser system according to claim 2, wherein, During the marking process, the marking control unit monitors the intensity of the plasma glow by the built-in photodetector, and modifies the alternating timing and pulse duty cycle in real time through closed-loop control to keep the etching depth consistent on the surfaces of various materials.

4. The high-speed precision marking device based on a dual-wavelength laser system according to claim 3, wherein During the marking process, the marking control unit sets the spot overlap ratio on each marking trajectory, and through the coordinated scheduling of the overlap ratio and the cross timing, suppresses the spot misalignment phenomenon caused by different wavelengths, and performs segmented weighting on the integration time window of the glow intensity to achieve rapid compensation for the instantaneous thermochromic effect of different materials.

5. The high-speed precision marking device based on a dual-wavelength laser system according to claim 4, wherein, When the post-processing unit scans the micro-region of the engraved groove again with the low-energy long pulse of the second wavelength laser, it simultaneously sprays a micro-mist cooling gas to reduce the color drift caused by heat accumulation and improve the surface finish.

6. The high-speed precision marking device based on a dual-wavelength laser system according to claim 5, characterized in that, The wavelength range of the first wavelength laser is in the near-infrared band; the wavelength range of the second wavelength laser is in the visible light band; the first wavelength laser and the second wavelength laser are coupled into the common galvanometer channel through a coaxial beam combiner, and the wavelength switching instruction is completed by the real-time operating system no less than twice within a marking cycle.

7. The high-speed precision marking device based on a dual-wavelength laser system according to claim 5, characterized in that After the post-processing unit obtains the marking contour through confocal imaging, it performs pixel-level edge filtering to identify the notch area containing acute-angled vertices, and limits the local re-engraving path to only cover the inner side of the boundary of the notch area to avoid secondary thermal impact on the qualified area.

8. The high-speed precision marking device based on a dual-wavelength laser system according to claim 7, wherein, The process of the wavelength adaptation mapping unit constructing the multi-level power-pulse combination mapping table for the first wavelength and the second wavelength includes: reading the wavelength priority queue sorted by absorption efficiency; then, for each material to be processed, calling the absorption threshold, thermal diffusivity, surface roughness, and reflectance entries stored in the multi-material database, and determining the minimum starting power and the safety upper limit power corresponding to the first wavelength and the second wavelength respectively by means of the one-by-one comparison rule; then establishing a multi-level power gradient in the first wavelength channel in an equally spaced increasing manner, and matching each power gradient with a pulse width and an intermittent window adapted to its thermal load to form an initial power-pulse sub-table for the first wavelength; simultaneously, constructing a corresponding multi-level power-pulse sub-table in the second wavelength channel according to the reflectance weight of the material; then interleaving and merging the two groups of initial power-pulse sub-tables in the order of the scanning path segments to generate a multi-level power-pulse combination mapping table with dual-wavelength linkage, and inserting three types of labels, namely the preheating section, the constant section, and the ending section, during the merging process to identify the power transition stage; then, according to the multi-level power-pulse combination mapping table, generating an independent energy scheduling curve for the material through the time series expansion algorithm, which includes a power-up buffer section, a steady-state processing section, and a power-down heat suppression section; finally, writing the energy scheduling curve into the cache area and binding the material identification code for subsequent calling according to the material during the real-time scanning process, thus completing the entire mapping generation process.

9. The high-speed precision marking device based on a dual-wavelength laser system according to claim 8, wherein, When calling the multi-material database, it also includes: instantaneously sampling the reflectance of the target material using an embedded reflectance monitoring probe, and comparing the sampling result with the historical reflectance mean value of the material in the database. When the difference exceeds the set tolerance, the database entry is automatically updated and then the power-pulse sub-table is executed.

10. The high-speed precision marking device based on a dual-wavelength laser system according to claim 9, characterized in that, After automatically updating the database entry, a low-power pre-etch test is triggered. A standardized calibration line is marked on the surface of the target material and its etching depth is measured instantaneously. When the measured value is within the preset depth range, the update is confirmed to be effective; otherwise, the modification is rolled back and the two groups of power-pulse sub-tables are recalculated.

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