A homogenizing diffractive optical element for laser processing

Abstract

The application belongs to the field of laser precision machining, and discloses a homogenization diffraction optical element for laser machining. The element comprises an integrated element body, a homogenization light control unit, a displacement sensing unit, a parameter acquisition unit and a data processing and evaluation unit. The homogenization light control unit reshapes the incident Gaussian light beam into a flat-top light spot; the displacement sensing unit detects displacement and positioning deviation in real time; the parameter acquisition unit acquires axial force, torsion, drilling temperature and drilling chip comprehensive characteristics through hardware synchronous triggering; the data processing and evaluation unit performs Kalman filtering and nonlinear normalization processing on the acquired parameters, constructs an evaluation formula based on ANOVA and PLS, calculates a drilling performance index P, and feeds back the regulation and control of the homogenization light control unit according to the grading result to form a closed-loop control. The application highly integrates the functions of homogenization, sensing, acquisition and evaluation, realizes quantitative evaluation and intelligent optimization of the laser drilling process of copper alloy and other materials, and improves the machining quality and efficiency.

Description

Technical Field

[0001] This invention belongs to the field of laser precision processing technology, specifically relating to a uniform light diffraction optical element for laser processing, and more particularly to an intelligent uniform light diffraction optical element integrating sensing, acquisition and closed-loop control functions. Background Technology

[0002] Laser precision machining technology, especially laser-assisted drilling technology, is increasingly widely used in high-precision manufacturing fields such as electronic components and aerospace structural parts. Copper alloys, due to their excellent electrical and thermal conductivity and mechanical properties, have become core materials in these fields. In laser-assisted drilling, the energy distribution of the incident laser beam directly affects the machining quality. Traditional laser beams are mostly Gaussian distributed, with excessively high energy at the center and insufficient energy at the edges, easily leading to problems such as overheating of the machining center and insufficient edge treatment. Therefore, diffractive optical elements (DOEs), with their precise optical wave diffraction control capabilities, are widely used in beam shaping. DOEs can reshape a Gaussian distributed laser beam into a flat-topped spot with uniform energy distribution, thereby effectively improving the uniformity of the heat-affected zone, reducing machining defects, and improving hole wall quality.

[0003] However, existing uniform diffraction optical elements and related technology systems used in laser processing, especially in the drilling of copper alloys, still have the following significant technical shortcomings:

[0004] First, the homogenizing element has a single function and insufficient system integration. Traditional homogenizing DOEs only have a single laser spot homogenization function, without displacement sensing, processing parameter acquisition, performance evaluation, and closed-loop control units. In practical applications, to achieve process monitoring and quality control, an additional independent sensing and detection system and performance evaluation module must be added. This split structure not only leads to redundancy in the overall equipment structure, large space occupation, and poor adaptability, making it difficult to meet the requirements of compact laser drilling stations and harsh dust conditions, but also easily causes signal interference and data interaction delays between independent units, reducing the reliability and response speed of the system (for example, see CN119270518B, CN121423893A). Although there are existing technologies that integrate multiple optical functions on the same substrate (e.g., US6069737A), their integration scope is limited to pure optical functions such as beam splitting and polarization, and does not involve deep integration with processing sensing, data evaluation, and control functions.

[0005] Secondly, there is a lack of quantitative evaluation standards and methods for the drilling performance of copper alloys. Copper alloys with different compositions and heat treatment states (such as T2 copper, H62 brass, beryllium copper, etc.) exhibit significant differences in machinability. Existing technologies mostly rely on operator experience to qualitatively judge the difficulty of the drilling process, or on a rough assessment based on a single physical quantity (such as monitoring only cutting force, see "Research on Evaluation Methods of Machinability of Copper and Copper Alloys"). There is a lack of a comprehensive quantitative evaluation system that integrates multiple physical parameters (force, heat, chip morphology, etc.) with scientifically and objectively allocated weights. This results in key process parameters such as laser power, drilling speed, and tool selection being unable to be precisely and adaptively optimized according to material characteristics, easily leading to problems such as low drilling efficiency, poor workpiece surface quality, and severe tool wear.

[0006] Secondly, the precision of machining parameter acquisition and data processing technology is insufficient. In existing split-type acquisition schemes, because each sensor operates independently and is mostly triggered by software, there is a lack of hardware synchronization mechanisms. This results in significant time misalignment (usually millisecond-level errors) in the acquisition of key parameters such as axial force, torque, and temperature, leading to poor data alignment accuracy and making it difficult to accurately reflect the machining state at the same moment. Simultaneously, the data processing methods are relatively crude. For example, linear normalization methods are often used to handle strongly nonlinear characteristic parameters in the drilling process (such as the complex coupling relationship between force, heat, and material removal rate), leading to distorted evaluation results. Furthermore, parameter weight settings rely heavily on subjective manual assignment, lacking rigorous verification based on statistical significance.

[0007] Finally, existing systems cannot form effective closed-loop control, resulting in poor processing stability and consistency. While existing laser processing equipment (such as CN112828466B) discloses image-based closed-loop control methods, its feedback parameters are singular (based solely on visual offset information), and its sensing units are not integrated with the DOE body. More commonly, most laser processing systems still employ open-loop control modes with preset fixed parameters, unable to dynamically adjust uniform beam parameters (such as spot size and energy distribution) and processing strategies based on real-time drilling conditions. This makes the system unable to adapt to the dynamic processing requirements of copper alloys with different cutting properties, hindering continuous optimization of processing quality and efficiency.

[0008] In summary, existing uniform beam diffraction optical elements and copper alloy laser drilling technology suffer from several drawbacks, including low functional integration, lack of quantitative evaluation methods, poor synchronization accuracy of multi-parameter acquisition, insufficient scientific rigor in data processing, and absence of intelligent closed-loop control. These shortcomings severely restrict the industrial application level and yield rate of copper alloy laser precision machining. Therefore, there is an urgent need to provide a novel uniform beam diffraction optical element that can overcome these deficiencies and integrate uniform beam control, multi-parameter sensing acquisition, quantitative performance evaluation, and closed-loop optimization control. Summary of the Invention

[0009] This invention aims to overcome the shortcomings of existing technologies and provide a uniform diffraction optical element for laser processing. This addresses the technical problems of existing uniform diffraction optical elements, such as limited functionality, low integration, and a lack of quantitative evaluation and closed-loop control of processing performance, leading to poor stability and difficulty in guaranteeing processing quality during laser processing. Specifically, the technical problems to be solved by this invention include:

[0010] 1. How to integrate multiple functional units such as uniform light control, displacement sensing, multi-parameter acquisition, and data processing and evaluation into a single optical element body to avoid the problems of redundancy, interference, and poor adaptability caused by traditional split structures;

[0011] 2. How to establish a quantitative processing performance evaluation model based on multiple physical parameters for laser processing (especially copper alloy drilling) to achieve scientific and real-time evaluation of processing status;

[0012] 3. How to achieve high-precision synchronous acquisition and processing of multiple parameters to eliminate data misalignment and nonlinear distortion;

[0013] 4. How to automatically adjust the uniform light control unit and external processing parameters based on the evaluation results to form a closed-loop control and achieve continuous optimization of the processing process.

[0014] To address the aforementioned technical problems, this invention provides a uniform diffraction optical element for laser processing, which adopts an integrated design that organically integrates multiple functional units onto the same element body and forms a complete intelligent closed-loop control system through signal interconnection.

[0015] Specifically, the technical solution adopted in this invention is as follows:

[0016] A uniform light diffraction optical element for laser processing includes an element body, a uniform light control unit, a displacement sensing unit, a parameter acquisition unit, and a data processing and evaluation unit.

[0017] The component body is made of an integrated substrate, preferably a high-temperature resistant optical material, to adapt to the harsh working conditions such as high temperature, dust, and vibration during laser processing. The component body is equipped with a dustproof and vibration-proof encapsulation structure to ensure the stable operation of the internal units.

[0018] The homogenizing and light-controlling unit is disposed on the component body and forms a micro-nano stepped diffraction structure on or inside the substrate surface based on the principle of optical wave diffraction. This unit is used to phase modulate the incident laser beam (preferably a laser with a wavelength of 1064nm), reshaping the traditional Gaussian distributed laser beam into a flat-top beam with uniform energy distribution. The homogenization accuracy of the homogenizing and light-controlling unit can reach ≤±3%, the diffraction efficiency can reach ≥90%, the stray light ratio can be controlled to ≤8%, and its beam size is continuously adjustable in the range of 50μm to 500μm. In terms of optical layout, the optical path of this unit is coaxially coupled to the center of the machining tool (such as a drill bit) of the workpiece being processed, so that the output flat-top beam can accurately cover the processing area (such as the drilling front area of ​​0.1 to 0.3mm). In addition, the component body may also be provided with a coaxial air curtain and / or dustproof window to protect the optical surface of the homogenizing and light-controlling unit from contamination by processing fumes and debris.

[0019] The displacement sensing unit is embedded in the component body (e.g., it can be located on the side of the component body or at the rear end of the machining spindle) and is used to detect displacement parameters and / or workpiece positioning deviations in real time during the machining process. In a preferred embodiment, the displacement sensing unit uses a laser displacement sensing component, which has a microsecond-level response speed and a measurement accuracy of ±0.01mm, and has an IP67 or higher protection rating. Combined with protective structures such as dust covers and air curtains, it can operate stably in harsh environments.

[0020] The parameter acquisition unit is also integrated into the component body and is used to acquire multiple processing parameters in real time during the machining process, including at least axial force, torque, drilling temperature, and comprehensive characteristics of drill chips. These parameters comprehensively reflect the mechanical, thermal, and material removal states of the machining area. To achieve high-precision synchronous acquisition, the parameter acquisition unit adopts a hardware synchronous triggering method, driving each acquisition component through a common clock source to ensure the time alignment accuracy between parameters, and the acquisition time jitter can be controlled within ≤100μs.

[0021] Specifically, the parameter acquisition unit may include one or a combination of the following components:

[0022] The piezoelectric force sensing component used to collect axial force has a typical range of 0 to 1000 N, an accuracy of ≤ ±0.3%FS, and a sampling frequency of up to 100 Hz.

[0023] The dynamic torque sensing component used to collect torque has a typical range of 0 to 5 N·m, an accuracy of ≤ ±0.1%FS, and a sampling frequency of up to 100 Hz.

[0024] The dual-color infrared temperature measurement component used to collect drilling temperature has a temperature measurement range of 0~300℃, an accuracy of ≤±0.5℃, a sampling frequency of up to 50Hz, and can be equipped with a coaxial air blowing dustproof structure.

[0025] The high-speed image acquisition component used to collect comprehensive features of drill cuttings has a typical frame rate of ≥1000fps and a resolution of 1080P. Combined with a backlit ring light source and image recognition algorithm, it can extract multi-dimensional features of drill cuttings, such as average diameter, aspect ratio, curling degree, chip breaking frequency, and chip removal success rate. These features are then quantified into a comprehensive feature value Ds through a preset fusion algorithm (such as weighted summation or principal component analysis).

[0026] The data processing and evaluation unit is signal-connected to the uniform light control unit, displacement sensing unit, and parameter acquisition unit (the connection can be made electrically or optically via built-in signal lines). This unit includes a filtering module, a normalization module, an evaluation model calculation module, and a feedback control module.

[0027] During operation, the data processing and evaluation unit first filters the collected raw processing parameters, preferably using the Kalman filter algorithm, which can achieve a filtering accuracy of over 96%, effectively removing environmental noise and electromagnetic interference.

[0028] Then, the filtered parameters are normalized to eliminate the influence of different dimensions and numerical ranges. To adapt to the highly nonlinear characteristics of laser processing (especially copper alloy drilling), this invention preferably employs a nonlinear normalization method. For any processing parameter X (such as axial force, torque, temperature, and comprehensive characteristics of drill chips), its normalized value... Calculate according to the following formula:

[0029]

[0030] Where k is an experimentally calibrated coefficient, adapted to the range of different parameters (e.g., k1 for axial force adapts to the 0-1000N range, k2 for torque adapts to the 0-5N·m range, k3 for temperature adapts to the 0-300℃ range, and k4 for drill cuttings comprehensive characteristics adapts to its quantized value range). As an alternative or supplementary option, this unit can also be configured with a linear normalization processing mode, the formula of which is...

[0031] .

[0032] Next, the data processing and evaluation unit calculates the processing performance evaluation index P based on a preset evaluation model. In a preferred embodiment of the present invention, the evaluation model is a weighted summation model, and its formula is as follows:

[0033]

[0034] in, , , , These are the normalized values ​​of axial force, torque, drilling temperature, and comprehensive characteristics of drill chips, respectively; α, β, γ, and δ are weighting coefficients, satisfying α + β + γ + δ = 1. To overcome the subjectivity of manual weighting, each weighting coefficient is determined based on significance analysis (such as ANOVA analysis) and partial least squares (PLS) fitting of a large amount of experimental data. For example, through experimental calibration, α can be taken as 0.35, β as 0.30, γ as 0.20, and δ as 0.15.

[0035] The calculated processing performance evaluation index P ranges from [0,1]. The closer the P value is to 1, the better the processing performance (e.g., low drilling force, low temperature, and excellent chip morphology). The closer the P value is to 0, the worse the processing performance.

[0036] Based on the P-value, the data processing evaluation unit classifies the current processing performance according to a preset grading standard. A typical grading standard is as follows:

[0037] Excellent (easy to process): P ≥ 0.8;

[0038] Good: 0.6 ≤ P < 0.8;

[0039] Generally: 0.4 ≤ P < 0.6;

[0040] Poor quality (difficult to process): P < 0.4.

[0041] Finally, the data processing and evaluation unit, based on the grading results, at least adjusts the output parameters of the uniform light control unit, and optionally sends process parameter adjustment commands to external laser processing equipment, forming a closed-loop control chain of "light control-processing-acquisition-evaluation-optimization". Exemplary control strategies include:

[0042] When P≥0.8, the current parameters of the uniform light control unit are maintained to adapt to higher processing speeds and laser energy;

[0043] When 0.6≤P<0.8, the spot energy distribution of the uniform light control unit is finely adjusted to further optimize the processing.

[0044] When 0.4≤P<0.6, the spot size of the uniform light control unit is reduced and the energy uniformity is optimized, while prompting external equipment to reduce the processing speed or enhance cooling.

[0045] When P < 0.4, the output parameters of the uniform light control unit are automatically optimized (such as significantly adjusting the phase distribution), and external devices are prompted to replace the tool or start auxiliary measures such as laser preheating.

[0046] As a complete workflow example of the present invention, the homogenizing diffraction optical element can operate according to the following steps:

[0047] 1. Installation and debugging: Install the components in the optical path of the laser processing equipment, perform coaxial coupling calibration, and preset the initial parameters of the uniform light control unit (such as spot size and energy distribution) and the basic process parameters of the external equipment;

[0048] 2. Uniform light processing and parameter acquisition: When processing is started, the uniform light control unit outputs a uniform light spot to illuminate the workpiece processing area, while the displacement sensing unit and parameter acquisition unit collect various processing parameters in real time.

[0049] 3. Data Processing and Evaluation: The data processing and evaluation unit filters and normalizes the collected parameters, calculates the processing performance evaluation index P, and classifies it.

[0050] 4. Parameter optimization: Based on the grading results, the data processing and evaluation unit automatically adjusts the output parameters of the uniform light control unit and / or sends process parameter adjustment instructions to external processing equipment; repeat the above processing, acquisition, evaluation, and adjustment steps until the processing performance reaches a stable and qualified state.

[0051] Compared with the prior art, the uniform diffraction optical element for laser processing provided by the present invention has the following beneficial effects:

[0052] 1. High integration and compact structure: This invention integrates four major functional units—uniform light control, displacement sensing, multi-parameter acquisition, and data processing and evaluation—onto a single optical element body for the first time. It eliminates the need for external independent detection and control modules, significantly reducing system redundancy and space occupation. It solves the problems of poor adaptability and susceptibility to interference in traditional split-type solutions, making it particularly suitable for compact workstations and harsh working conditions in laser processing.

[0053] 2. Establishing a Quantitative Evaluation Standard for Machining Performance: This invention constructs a weighted evaluation model based on four core parameters: axial force, torque, drilling temperature, and comprehensive characteristics of drill chips. By introducing nonlinear normalization, it accurately adapts to the strong nonlinear characteristics of laser processing of materials such as copper alloys. The weighting coefficients are obtained based on ANOVA significance analysis and PLS partial least squares fitting, avoiding the bias of subjective human assignment, making the evaluation results more scientific, accurate, and quantifiable, filling the gap in the lack of a unified evaluation standard in this field.

[0054] 3. High-precision, synchronized parameter acquisition: This invention employs a hardware synchronous triggering mechanism to achieve multi-parameter synchronous clock driving, controlling the acquisition time jitter to ≤100μs, ensuring precise alignment of parameters from different sources such as axial force, torque, temperature, and images in the time dimension. This provides a high-quality data foundation for subsequent data fusion and evaluation model calculations, significantly improving system reliability.

[0055] 4. Intelligent closed-loop control for continuous optimization of processing quality: This invention directly feeds back the evaluation results to the uniform light control unit and external processing equipment, realizing a complete closed loop of "light control-processing-acquisition-evaluation-optimization". The system can automatically adjust the spot shape and process parameters according to the real-time processing performance evaluation level without manual intervention, significantly improving the consistency and stability of processing and reducing tool wear and scrap rate.

[0056] 5. Strong adaptability and high reliability: This invention is specifically designed for harsh environments such as high temperature, dust, and vibration in laser processing. For example, it uses a substrate with a temperature resistance of ≥400℃, incorporates coaxial air curtains and dustproof windows, and provides IP67 protection and multiple air curtain protection for the sensing components. These measures effectively ensure the reliable operation of the components during long-term, high-intensity processing, extending their service life.

[0057] 6. Universality and scalability: The technical solution of this invention is not only applicable to laser-assisted drilling of copper alloys, but can also be extended to precision machining scenarios such as laser cutting, welding, and drilling of other metal materials (such as aluminum alloys, titanium alloys, stainless steel, etc.) by appropriately adjusting parameters (such as wavelength adaptation, weight coefficient recalibration, etc.), and has broad application prospects.

[0058] In summary, this invention overcomes many shortcomings of the prior art and realizes the leap from a single optical device to an intelligent, integrated, and closed-loop controlled core functional module for uniform light diffraction optical elements. This has important practical significance for improving the overall technical level of laser precision processing. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the structure of the uniform diffraction optical element for laser processing described in this invention;

[0060] Figure 2 for Figure 1 The internal functional unit layout and optical path diagram of the component shown are as follows;

[0061] Figure 3 This is a system framework and signal connection block diagram of the uniform light diffraction optical element described in this invention;

[0062] Figure 4 This is a flowchart illustrating the operation of the uniform light diffraction optical element described in this invention.

[0063] Explanation of the markings on the attached diagram:

[0064] 100. Component body; 110. Incident laser beam; 120. Uniform light spot; 200. Uniform light control unit; 210. Micro / nano stepped diffraction structure; 220. Coaxial air curtain inlet; 230. Dustproof window; 300. Displacement sensing unit; 310. Laser displacement sensor probe; 320. Dustproof cover; 400. Parameter acquisition unit; 410. Piezoelectric force sensing component; 420. Dynamic torque sensing component; 430. Dual-color infrared temperature measurement component; 44. 0. High-speed image acquisition component; 441. Backlight ring light source; 442. Side-blowing dustproof nozzle; 450. Hardware synchronization trigger module; 500. Data processing and evaluation unit; 510. Filtering module; 520. Normalization module; 530. Evaluation model calculation module; 540. Feedback control module; 600. External laser processing equipment; 610. Machining spindle; 620. Drilling tool; 630. Copper alloy workpiece; 640. Machining area; 650. Drill chips. Detailed Implementation

[0065] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention.

[0066] Reference Figures 1 to 4 This invention provides a uniform diffraction optical element for laser processing. For example... Figure 1 and Figure 2 As shown, the component includes an integrated component body 100, which is preferably made of optical glass or crystal material (such as fused silica, sapphire, etc.) with a temperature resistance of not less than 400°C to withstand the heat radiation and impact of high-temperature sputtering particles generated during laser processing. Inside and on the surface of the component body 100, a uniform light control unit 200, a displacement sensing unit 300, a parameter acquisition unit 400, and a data processing and evaluation unit 500 are integrated using micro-nano fabrication technologies (including but not limited to photolithography, reactive ion etching, electron beam writing, or nanoimprinting). The units are electrically connected and communicate bidirectionally via built-in signal lines (such as flexible circuit boards, wire bundles, or internal metallized wiring), eliminating the need for external independent modules. The overall structure is compact and highly reliable. Furthermore, dustproof and vibration-proof encapsulation structures (such as sealing rings, potting compound, and metal shielding covers) can be added to the periphery of the component body 100 to adapt to the harsh industrial environment of high dust, high vibration, and high humidity during laser drilling.

[0067] Specifically, the homogenizing and controlling unit 200 is disposed in the central region of the element body 100, located in the optical path of the incident laser beam 110. The surface or interior of this unit is etched with a micro / nano stepped diffraction structure 210, which is a two-dimensional or multi-step phase profile that modulates the phase of the incident laser beam based on the principle of optical wave diffraction. In this embodiment, the homogenizing and controlling unit 200 is optimized for infrared lasers with a wavelength of 1064 nm, reshaping the Gaussian-distributed incident laser beam 110 into a uniformly distributed light spot 120. In actual fabrication, the diffraction efficiency and homogenization accuracy can be controlled by adjusting the height, width, and number of steps of the micro / nano steps, achieving a homogenization accuracy ≤ ±3%, diffraction efficiency ≥ 90%, stray light ratio ≤ 8%, and the spot size can be continuously adjusted within the range of 50 μm to 500 μm (e.g., by adjusting the phase of the liquid crystal layer through applied voltage or by using a MEMS micromirror array to change the effective optical path). To ensure the precise application of the uniform light spot 120 to the processing area, the optical path of this unit employs coaxial coupling, aligning the output flat-top light spot with the central axis of the processing tool (such as a drill bit), ensuring the spot covers the workpiece's front-edge region within a 0.1–0.3 mm range. Furthermore, a dustproof window 230 and a coaxial air curtain inlet 220 are respectively provided on the laser incident side and / or exit side of the uniform light control unit 200. The coaxial air curtain inlet 220 is connected to an external compressed air or inert gas source, forming a high-speed air curtain during operation to continuously sweep the optical surface, preventing processing dust and metal debris from adhering to the surface of the micro / nano stepped diffraction structure 210, thereby ensuring long-term operational stability. The dustproof window 230 uses replaceable sapphire glass; even if scratches or contamination appear on the surface after long-term use, only the window needs to be replaced without disassembling the entire diffraction structure, significantly reducing maintenance costs.

[0068] The displacement sensing unit 300 is embedded and integrated on the side of the component body 100, preferably mounted on the side closer to the machining spindle. For example... Figure 2 As shown, the displacement sensing unit 300 includes a laser displacement sensor probe 310 and an external dust cover 320. The probe employs triangulation or confocal measurement principles, emitting a laser beam onto the workpiece surface and receiving the reflected light to detect the relative displacement between the tool and the workpiece, as well as the workpiece's positioning deviation, in real time during drilling. The displacement sensing unit 300 achieves a measurement accuracy of ±0.01mm and a response speed in the microsecond range, enabling timely detection of positioning deviations caused by workpiece clamping errors or thermal deformation. To adapt to harsh working conditions, the displacement sensing unit 300 meets an IP67 or higher protection rating. The dust cover 320 is also equipped with a transparent window and a miniature air curtain interface to further prevent dust accumulation from affecting measurement accuracy. When the detected displacement deviation exceeds a preset threshold (e.g., 0.02mm), the displacement sensing unit 300 immediately sends an alarm signal to the data processing and evaluation unit 500, allowing the system to adjust the machining path or pause machining in a timely manner to avoid producing defective products.

[0069] Parameter acquisition units 400 are distributed at different positions on the component body 100 to acquire multiple processing parameters in real time during the machining process, specifically including axial force Fz, torque M, drilling temperature T, and comprehensive characteristics of drill chips Ds. These parameters comprehensively characterize the processing state of the laser-assisted drilling process from three dimensions: mechanical, thermal, and material removal morphology. Figure 2 and Figure 3 As shown, axial force acquisition uses a piezoelectric force sensing component 410, which is embedded between the component body 100 and the flange surface connecting to the external processing equipment. It directly bears the axial reaction force during drilling, with a range of 0–1000 N, an accuracy of ±0.3%FS, and a sampling frequency of up to 100 Hz. Torque acquisition uses a dynamic torque sensing component 420, integrated inside the component body 100 at the bushing connecting to the machining spindle. It has a range of 0–5 N·m, an accuracy of ±0.1%FS, and a sampling frequency of 100 Hz. Drilling temperature acquisition uses a dual-color infrared thermometer component 430. Its probe is tilted and installed on the side of the component body 100 closest to the machining area, with the field of view precisely aligned with the tool-chip contact area. Dual-color infrared thermometry eliminates measurement errors caused by smoke and dust and emissivity variations. The temperature range is 0–300℃, with an accuracy of ±0.5℃ and a sampling frequency of 50 Hz. It is also equipped with a coaxial air-blowing dustproof structure, using compressed air to continuously blow clean the lens surface to prevent smoke and dust adhesion. The comprehensive feature acquisition of drill chips utilizes a high-speed image acquisition component 440, which includes a high-speed camera (frame rate ≥ 1000fps, resolution 1080P), a backlit ring light source 441, and a side-blowing dustproof nozzle 442. The high-speed camera is mounted on the bottom or side of the component body 100, with the lens facing the path of drill chip splashes in the machining area. The backlit ring light source 441 provides uniform back illumination, making the outline of the drill chips 650 clearly discernible, facilitating subsequent image recognition. The side-blowing dustproof nozzle 442 continuously sprays compressed air to prevent drill chips from adhering to the lens surface, ensuring clarity during long-term continuous acquisition. The acquired drill chip images are processed in real time using a built-in image recognition algorithm to extract five sub-features: average diameter, aspect ratio, curling degree, chip breaking frequency, and chip removal success rate. A comprehensive quantitative value Ds is calculated according to a preset fusion algorithm (e.g., weighted geometric mean, entropy weight method, or principal component analysis). This Ds value comprehensively reflects key drilling states such as chip breaking, chip removal, tool entanglement, and chip blockage.

[0070] To ensure time alignment accuracy among multiple parameters, the parameter acquisition unit 400 can further integrate a hardware synchronization trigger module 450. This hardware synchronization trigger module 450 consists of a high-precision crystal oscillator (e.g., 10MHz, temperature drift ≤ ±2ppm) and a programmable logic device (CPLD or FPGA). The CPLD generates multiple synchronization pulse signals based on the reference clock generated by the crystal oscillator: Channel 1 outputs a rising edge every 10ms (i.e., 100Hz), simultaneously triggering the piezoelectric force sensing component 410, the dynamic torque sensing component 420, and the dual-color infrared temperature measurement component 430 to perform sampling conversion; Channel 2 outputs a pulse every 100ms (i.e., 10Hz), triggering the high-speed image acquisition component 440 to perform exposure and image capture, and the pulses of Channel 2 are precisely aligned in time with a specific pulse of Channel 1 (e.g., the 10th pulse). Because all trigger signals originate from the same clock source and are transmitted through equal-length wiring on the circuit board, the acquisition time jitter between channels can be strictly controlled within 100 microseconds (μs), far superior to the millisecond-level random jitter typically present in traditional software triggering methods. This high-precision hardware synchronous acquisition mechanism ensures a one-to-one correspondence between axial force, torque, temperature, and drill cuttings images in time, providing a reliable data foundation for subsequent data fusion and evaluation model calculations.

[0071] The data processing and evaluation unit 500 is housed in a closed cavity within the component body 100, and includes an embedded microprocessor (e.g., an ARM Cortex-M7, RISC-V chip, or FPGA), a memory chip, and a signal conditioning circuit. This unit communicates bidirectionally with each component of the uniform light control unit 200, the displacement sensing unit 300, and the parameter acquisition unit 400 via signal connection lines. Figure 3 As shown, the data processing and evaluation unit 500 is functionally divided into a filtering module 510, a normalization module 520, an evaluation model calculation module 530, and a feedback control module 540. During operation, the filtering module 510 first performs Kalman filtering on the originally acquired axial force Fz, torque M, and drilling temperature T. Kalman filtering, by establishing a state-space model, can effectively remove Gaussian noise and spike interference introduced by mechanical vibration, electromagnetic interference, etc., achieving a filtering accuracy of over 96%, making the processed signal smoother and more accurately reflecting the inherent changes in the machining process. The filtered data is then sent to the normalization module 520. Because the dimensions and numerical ranges of different parameters vary greatly (axial force is in the hundreds of Newtons range, torque is in the Newton-meter range, temperature is in the hundreds of degrees Celsius range, and the comprehensive characteristics of drill chips are dimensionless), and the laser drilling process of metal materials such as copper alloys typically exhibits strong nonlinear characteristics (e.g., the exponential relationship between cutting force and cutting speed, and the saturation effect between temperature and material softening), this embodiment preferably uses a nonlinear normalization method. Specifically, for the axial force Fz (in N), the normalized value According to the formula Calculation; for torque M (unit N·m), according to Calculation; for drilling temperature T (unit: °C), according to Calculation; for the comprehensive characteristic Ds of drill cuttings (dimensionless), according to Calculation. Here, k1, k2, k3, and k4 are experimental calibration coefficients, each adapted to the range of each parameter. The determination method for these calibration coefficients is as follows: Select typical copper alloy samples (such as T2 copper and H62 brass), conduct drilling experiments within a wide range of process parameters covering easy to machine and difficult to machine, simultaneously collect the values ​​of each parameter and record the corresponding machining quality (such as surface roughness and tool wear), and then fit an exponential function parameter through nonlinear regression that makes the normalized parameter approach 1 under optimal process conditions and approach 0 under worst process conditions. For example, for the axial force range 0–1000N, k1 is calibrated to 0.005; for the torsional force range 0–5N·m, k2 is calibrated to 0.2; for the temperature range 0–300℃, k3 is calibrated to 0.02; and for the comprehensive characteristic range of drill chips 0–10, k4 is calibrated to 0.5. As an alternative or supplementary method, the normalization module 520 can also be configured with a linear normalization mode, i.e., according to... Perform calculations, where and These are the maximum and minimum empirical values ​​of the parameter within the preset range, respectively. Users can switch between the two normalization modes via host computer software according to the linearity of the actual process, increasing the flexibility and applicability of the invention.

[0072] After normalization, the evaluation model calculation module 530 calculates the processing performance evaluation index P based on a preset evaluation model. In this embodiment, the evaluation model is a weighted summation model, and its specific calculation formula is as follows: Wherein, α, β, γ, and δ are the weighting coefficients for axial force, torque, drilling temperature, and comprehensive characteristics of drill chips, respectively, and satisfy α+β+γ+δ=1. To avoid the subjectivity of manual weighting, the weighting coefficients are determined using a statistical method: a large amount of experimental data on copper alloy drilling (each set of data includes four normalized parameters and corresponding comprehensive machining quality labels) is collected. First, ANOVA (analysis of variance) is used to rank the significance level of each parameter on machining quality to determine the degree of influence of each parameter; then, partial least squares (PLS) is used to fit regression coefficients, and the normalized regression coefficients are used as weighting coefficients. Through this data-driven approach, this embodiment calibrates α=0.35, β=0.30, γ=0.20, and δ=0.15. This weighting allocation reflects the physical law that axial force has the greatest impact on drilling performance, followed by torque, while temperature and comprehensive characteristics of drill chips are also not negligible. The calculated P value ranges from [0,1]. The closer the P value is to 1, the better the processing performance (i.e., small axial force, small torque, low temperature, fine chips and smooth chip removal). The closer the P value is to 0, the worse the processing performance (i.e., large axial force, large torque, high temperature, coarse chips or entangled chips).

[0073] After the evaluation model calculation module 530 outputs the P value, the feedback control module 540 rates the current processing performance according to the preset grading standard and generates corresponding control commands based on the rating result. An example of the grading standard is as follows: When P ≥ 0.8, it is judged as "Excellent," indicating a stable processing process with force and thermal parameters within ideal ranges. The feedback control module 540 sends a command to the uniform light control unit 200 to maintain the current output parameters and simultaneously suggests to the external laser processing equipment 600 that a higher drilling speed and laser energy can be adapted to further improve efficiency; when 0.6 ≤ P < 0.8, it is judged as "Good," indicating a relatively stable processing process with occasional slight fluctuations. The feedback control module 540 fine-tunes the spot energy distribution of the uniform light control unit 200 (e.g., by changing the duty cycle of the micro / nano stepped diffraction structure 210 or applying a small voltage to adjust the liquid crystal phase) to further optimize energy uniformity and simultaneously sends a suggestion to the external device to maintain normal processing; when 0.4 ≤ P < 0.6, it is judged as "Good." In the "General" level, the force and temperature fluctuate greatly during processing, and the chip size is uneven. The feedback control module 540 automatically reduces the spot size (e.g., from 200μm to 150μm) and enhances energy uniformity. At the same time, it sends a prompt signal to the external laser processing equipment 600 to reduce the drilling speed and increase the coolant flow through the external communication interface. When P<0.4, it is judged as the "Poor" level. At this time, the processing performance is poor, and problems such as accelerated tool wear, workpiece thermal deformation, and even chip blockage are likely to occur. The feedback control module 540 significantly optimizes the phase distribution of the uniform beam control unit 200 (e.g., switching to another set of diffraction structures with a preset high uniformity and large flat top mode). At the same time, it sends a strong suggestion to the external laser processing equipment 600 to replace the tool with a more suitable one or to start laser preheating enhancement. In the aforementioned control commands, the adjustment signal sent to the uniform light control unit 200 takes effect in real time through the built-in drive circuit, while the prompts or commands sent to the peripheral devices are implemented through standard industrial fieldbuses (such as RS232, EtherCAT, Profinet, etc.), thus forming a complete closed-loop control link of "light control - processing - acquisition - evaluation - optimization".

[0074] The following is combined Figure 4The complete workflow diagram shown illustrates the usage of this invention. In step S1, the installation and debugging stage, the operator installs the component described in this invention between the optical output end of the laser processing equipment 600 and the processing spindle 610 via a standard mechanical interface. The component position is adjusted so that the center of the incident laser beam 110 is aligned with the optical center of the uniform light control unit 200, while ensuring that the output uniform light spot 120 is coaxial with the center of the drilling tool 620. The upper computer software is connected through the debugging interface on the component body 100, and the built-in self-test and calibration program is started. This program automatically checks the zero point of the displacement sensing unit 300, the noise level of each channel of the parameter acquisition unit 400, and automatically calibrates the focal length and brightness of the high-speed camera using a built-in standard whiteboard or calibration block. Based on the material (e.g., T2 copper, H62 brass, beryllium copper, etc.), thickness, and expected machining accuracy of the copper alloy workpiece 630 to be processed, the initial parameters of the uniform light control unit 200 (e.g., spot size 200μm, energy distribution mode flat-top uniform mode) and the basic process parameters of the external equipment (e.g., laser power 200W, spindle speed 3000rpm, feed rate 50mm / min) are preset in the host computer software or directly in the built-in menu of the component. In step S2, the uniform light processing and parameter acquisition stage, the laser processing equipment 600 is started to begin drilling the copper alloy workpiece 630. The incident laser beam 110 is reshaped into a uniform flat-top uniform light spot 120 after passing through the uniform light control unit 200, and is precisely irradiated in a coaxial manner on the front area 640 of the drilling tool 620 (i.e., within 0.1 to 0.3mm of the leading edge of the contact area between the tool and the workpiece). This area is preheated at a constant temperature to soften it and reduce cutting resistance. Meanwhile, the displacement sensing unit 300 monitors the axial displacement of the machining spindle 610 and the positioning deviation of the workpiece in real time. The parameter acquisition unit 400, driven by the hardware synchronization trigger module 450, synchronously acquires axial force Fz, torque M, drilling temperature T, and drill chip images according to a preset sampling frequency (axial force / torque 100Hz, temperature 50Hz, image 10Hz). All data are packaged into data frames with a unified timestamp and transmitted to the data processing and evaluation unit 500 via a high-speed bus. In step S3, the data processing and evaluation stage, the data processing and evaluation unit 500 first performs Kalman filtering on the raw data to eliminate noise interference, and then uses a nonlinear normalization formula to calculate... , , and The P-value is calculated by substituting it into the evaluation model, and the drilling performance level is determined according to the grading standard. For example, assuming that at a certain moment, Fz=280N, M=1.2N·m, T=185℃ are collected, and Ds=3.5 is obtained through image analysis, the drilling performance level is calculated using the above calibration coefficients. =0.753、 =0.213、 =0.975、 =0.826, after substituting the weighting coefficient, we get P=0.6464, which is judged as "good". In the parameter optimization stage of step S4, based on the evaluation result of "good", the feedback control module 540 sends a command to the uniform light control unit 200 to fine-tune the spot energy distribution, and at the same time sends a prompt to the peripheral device to maintain or slightly increase the feed speed. If the P value obtained by subsequent acquisition and calculation further decreases to 0.51 (general level), the system will automatically perform more aggressive adjustments: reduce the spot size to 150μm, enhance energy uniformity, and force the external device to reduce the drilling speed to 40mm / min and increase the coolant flow rate. After the adjustment is completed, the system automatically returns to step S2 and repeats the cycle of uniform light processing, parameter acquisition, data processing and optimization until the processing performance reaches and stabilizes at the good or excellent level, thereby realizing continuous adaptive optimization of the processing process.

[0075] To verify the technical effects of this invention, the applicant conducted a comparative experiment. The experimental conditions were as follows: workpiece material: T2 copper plate, thickness 3mm; fiber laser wavelength: 1064nm; drilling tool: 2mm diameter carbide drill bit. The control group (Group A) used a traditional uniform light DOE (without sensor acquisition and closed-loop function) with fixed process parameters (laser power 250W, spindle speed 4000rpm, feed rate 60mm / min); the experimental group (Group B) used the component described in this invention and enabled the closed-loop control function. Experimental results show that: the average axial force of group B was 278N, a decrease of 14.5% compared to group A (325N); the average drilling temperature was 182℃, a decrease of 13.3% compared to group A (210℃); the chip morphology changed from long, ribbon-like chips to fine C-shaped chips, resulting in smooth chip removal; the tool wear (wear width VB on the flank face after drilling 50 holes) was 0.07mm, a decrease of 41.7% compared to group A (0.12mm); the burr height at the hole entrance was significantly reduced; and the machining efficiency increased by approximately 20.7%. These experimental data fully demonstrate the significant advantages of this invention in reducing cutting force and thermal load, improving chip morphology, extending tool life, and improving machining efficiency and quality.

[0076] Furthermore, it should be noted that this invention is not only applicable to laser-assisted drilling of copper alloys, but through simple parameter recalibration (e.g., changing the diffraction structure to suit other wavelengths, recalibrating the normalization coefficients and weighting coefficients, etc.), it can be extended to various precision machining scenarios such as laser cutting, laser welding, and laser drilling of materials such as aluminum alloys, titanium alloys, stainless steel, and high-temperature alloys. The specific embodiments described above are merely preferred embodiments of this invention and are not intended to limit the invention. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and principles of this invention, such as further integrating the displacement sensing unit with the beam homogenization and control unit (using the same laser beam to simultaneously achieve beam homogenization and ranging), or expanding the parameter acquisition unit to include acoustic emission sensors, vibration sensors, etc. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A uniform diffraction optical element for laser processing, characterized in that, include: Component body (100); uniform light control unit (200), disposed on the component body (100), used to diffract and shape the incident laser beam (110) to form a uniform light spot (120). The displacement sensing unit (300) is integrated on the component body (100) and is used to detect displacement parameters and / or positioning deviations; the parameter acquisition unit (400) is integrated on the component body (100) and is used to acquire the comprehensive characteristics of axial force, torque, drilling temperature and drill chips (650) in real time, and the acquisition is driven by the same source clock by hardware synchronous triggering. The data processing and evaluation unit (500) is located inside or on the component body (100) and is connected to the uniform light control unit (200), the displacement sensing unit (300), and the parameter acquisition unit (400) respectively. It is used to filter and normalize the acquired parameters, calculate the processing performance evaluation index based on the preset evaluation model and classify it, and adjust the output parameters of the uniform light control unit (200) according to the classification results to form a closed-loop control. The component is adapted to be used in conjunction with an external laser processing equipment (600), which is equipped with a processing spindle (610) and a drilling tool (620) and can perform drilling processing on the processing area (640) of the copper alloy workpiece (630) and generate drill chips (650).

2. The uniform diffraction optical element according to claim 1, characterized in that, The homogenizing and controlling unit (200) includes a micro-nano stepped diffraction structure (210), a coaxial air curtain inlet (220), and a dustproof window (230). The micro-nano stepped diffraction structure (210) is used to modulate the phase of the incident laser beam (110). The coaxial air curtain inlet (220) can be connected to the airflow to form a coaxial protective air curtain. The dustproof window (230) is set on the laser incident side and / or the exit side to achieve dust protection. The homogenization accuracy of this unit is ≤±3%, the diffraction efficiency is ≥90%, the stray light is ≤8%, the temperature resistance is ≥400℃, the spot size is continuously adjustable from 50μm to 500μm, and the optical path is coaxially coupled with the center of the drilling tool (620).

3. The uniform diffraction optical element according to claim 1, characterized in that, The displacement sensing unit (300) includes a laser displacement sensor probe (310) and a dust cover (320); the laser displacement sensor probe (310) is embedded in the component body (100) and is used to emit and receive detection lasers; the dust cover (320) is placed on the outside of the probe to achieve dust protection; the unit has a measurement accuracy of ±0.01mm, a response speed of microseconds, and an IP67 or higher protection level.

4. The uniform diffraction optical element according to claim 1, characterized in that, The parameter acquisition unit (400) includes a piezoelectric force sensing component (410), a dynamic torque sensing component (420), a dual-color infrared temperature measurement component (430), a high-speed image acquisition component (440), a backlight ring light source (441), a side-blowing dustproof nozzle (442), and a hardware synchronous triggering module (450). The backlight ring light source (441) is equipped with a high-speed image acquisition component (440) to provide uniform backlight illumination. The side-blowing dustproof nozzle (442) is used to blow away lens dust. The hardware synchronization trigger module (450) realizes the synchronous acquisition of multiple components from the same source clock. Among them, the piezoelectric force sensing component (410) has a range of 0 to 1000 N and an accuracy of ≤ ±0.3%FS, the dynamic torque sensing component (420) has a range of 0 to 5 N·m and an accuracy of ≤ ±0.1%FS, the dual-color infrared temperature measuring component (430) has a temperature measuring range of 0 to 300℃ and an accuracy of ≤ ±0.5℃, and the high-speed image acquisition component (440) has a frame rate of ≥ 1000fps and an overall sampling time jitter of ≤ 100μs.

5. The uniform diffraction optical element according to claim 1, characterized in that, The data processing and evaluation unit (500) includes a filtering module (510), a normalization module (520), an evaluation model calculation module (530), and a feedback control module (540). The filtering module (510) is used for parameter noise reduction, the normalization module (520) is used for parameter standardization, the evaluation model calculation module (530) is used for performance index calculation, and the feedback control module (540) is used for outputting control commands. The filtering module adopts the Kalman filtering algorithm with a filtering accuracy of ≥96%. The comprehensive feature Ds of the drill cuttings (650) is a quantitative value that integrates the average diameter, aspect ratio, curling degree, chip breaking frequency, and chip removal success rate of the drill cuttings.

6. The uniform diffraction optical element according to claim 1, characterized in that, Normalization includes two modes: nonlinear normalization and linear normalization; the formula for nonlinear normalization is: ， Where X represents the original parameter value collected. Here are the normalized parameter values, and k is the experimental calibration coefficient that matches the range of the corresponding parameter. The axial force, torque, drilling temperature and comprehensive characteristics of drill chips in the machining parameters are each independently normalized using their respective nonlinear normalization formulas. The linear normalization formula is: ， in, , These are the maximum and minimum acquisition values ​​of the corresponding parameters within the preset range, respectively.

7. The uniform diffraction optical element according to claim 1, characterized in that, The evaluation model is a weighted summation model, and the formula for calculating the processing performance evaluation index P is: ； in, , , , These are the normalized values ​​of axial force, torque, drilling temperature, and comprehensive characteristics of drill chips, respectively; α, β, γ, and δ are weighting coefficients, and α+β+γ+δ=1; the weighting coefficients are determined by significance analysis and partial least squares fitting.

8. The uniform diffraction optical element according to claim 7, characterized in that, Control is based on P-value grading: P≥0.8 is excellent, maintaining the parameters of the uniform light control unit (200); 0.6 ≤ P < 0.8 is considered good; fine-tune the energy distribution of the light spot. 0.4≤P<0.6 is considered normal. Reducing the spot size and optimizing uniformity suggests reducing the processing speed or increasing cooling. P < 0.4 indicates poor performance. Optimize output parameters and prompt to replace the tool (620) or start auxiliary preheating.

9. The uniform diffraction optical element according to claim 1, characterized in that, It also includes an external laser processing device (600), which includes a processing spindle (610), a drilling tool (620), a copper alloy workpiece (630), a processing area (640), and drill chips (650); the processing spindle (610) drives the drilling tool (620) to perform drilling processing on the processing area (640) of the copper alloy workpiece (630), and drill chips (650) are generated during the processing.

10. The uniform diffraction optical element according to claim 1, characterized in that, The workflow includes: S1. Installation and debugging: Install the component in the optical path of the laser processing equipment and perform coaxial coupling calibration, and preset the initial parameters of the uniform light control unit (200); S2. Uniform light processing and parameter acquisition: When processing is started, the uniform light control unit (200) outputs a uniform light spot (120) to irradiate the workpiece processing area (640), and at the same time, the parameter acquisition unit (400) and the displacement sensing unit (300) acquire various processing parameters in real time. S3. Data processing and evaluation: The data processing and evaluation unit (500) filters and normalizes the collected parameters, calculates the processing performance evaluation index and classifies it. S4. Parameter optimization: Based on the grading results, the data processing evaluation unit (500) automatically adjusts the output parameters of the uniform light control unit (200) and / or sends process parameter adjustment instructions to external processing equipment, repeating steps S2 to S4 until the processing performance reaches a stable and qualified state.

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