A follow-up laser processing device and control method thereof

Abstract

The present invention discloses a follow-up laser processing device and a control method thereof, comprising a laser processing unit and an optical detection unit, wherein the laser processing unit is used to emit a laser beam and converge it into a processing laser spot, and the optical detection unit is used to emit detection light, which returns to a spectrometer after reaching the processing surface, and the spectrometer is used to measure the distance between the laser processing head and the processing surface. The present invention can be applied to various materials, used for cutting, drilling or surface treatment, not limited to metal materials; height information can be directly obtained through a single measurement, and the measurement accuracy can reach micrometer or even sub-micrometer measurement accuracy, which fully matches the current laser focusing depth parameters and achieves the best processing effect.

Description

Technical Field

[0001] The invention relates to a follow-up laser processing device and a control method thereof, belonging to the technical field of laser processing. Background Art

[0002] In the fields of laser precision cutting, drilling and surface treatment, it is necessary to accurately control the position of the laser focus spot on the surface of the workpiece, otherwise it will affect the quality and efficiency of the processing. The commonly used method is to install a capacitive sensor on the laser processing head, and control the capacitance value to be constant by detecting the capacitance and adjusting the height of the laser processing head to achieve the same distance between the processing head and the workpiece, but this method is only applicable to metal materials; Han's Laser proposed a method based on installing an auxiliary optical measurement device at the processing head position, which can be combined with the adjustment of the Z-axis adjustment platform to find the best processing position, which is suitable for the processing of various materials. However, this method can only measure the reflected light intensity signal. If the processing surface is located above or below the processing focus position, the light intensity signal will be attenuated, so the distance information cannot be directly obtained based on a single light intensity signal. It needs to be combined with the scanning of the Z axis, resulting in a decrease in the measurement speed or an expensive high-speed precision motion platform is required to make the detection speed match the laser processing efficiency; In addition, the size and weight of the processing head are significantly increased, which correspondingly increases the volume of the equipment and the motion drive power.

[0003] In addition, at present, when spectral confocal is needed for precision measurement in laser precision processing, the spectral confocal measurement device is generally installed as an independent device near the laser processing head or an independent motion control system drives its scanning measurement. Some problems caused include: 1) It is difficult to make the relative position of the laser processing head and the confocal ranging probe relatively consistent, and the relative position needs to be precisely adjusted or compensated, which increases the complexity of equipment control and use process; 2) The laser processing device and the confocal ranging are two independent control systems, and the synchronization of processing and detection is difficult to ensure; 3) When the processing position point and the detection point are close, the laser signal will have a strong interference with the spectral signal. It is precisely because of the relative independence of the two systems that error information appears in the detection signal measurement process. Summary of the invention

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a follow-up laser processing device that can be applied to a variety of materials and does not require Z-axis scanning when the processing surface is located above or below the processing focus position.

[0005] Technical solution: To solve the above technical problems, a follow-up laser processing device of the present invention includes a laser processing unit and an optical detection unit. The laser processing unit is used to emit a laser beam and converge it into a processing laser spot. The optical detection unit is used to emit detection light. After the detection light reaches the processing surface, it returns to the distance measuring unit. The distance measuring unit includes a spectrometer, which is used to measure the distance between the laser processing head and the processing surface. When the processing surface is outside the processing focus, the Z axis controls the follow-up to reach the processing focus. The detection light emitted by the optical detection unit has a certain spectral width. In order to avoid interference with the laser signal, its spectrum can be selected to avoid the spectral frequency of the processing laser beam; in order to increase the measurement range, or to match lasers of different wavelengths, it can also be processed / detected by time sharing, or the laser interference signal can be identified and processed by software. When the detection light passes through the focusing unit, the light sources of the detection light at different frequencies are focused at different positions due to the dispersion of the focusing unit, which is not an ideal light point. Therefore, only the light source focused on the processing surface enters the spectrometer along the original path.

[0006] Furthermore, when the laser processing unit is a conventional laser, the laser processing unit emits a laser beam, a beam expander is provided on one side of the laser beam, a beam splitter is provided on one side of the beam expander, and a focusing unit is provided on one side of the beam splitter. The laser beam is collimated by the beam expander and then focused into a processing laser spot by the focusing unit.

[0007] Furthermore, a fiber optic splitter / coupler 1 is provided on one side of the optical detection unit, a collimator is provided on one side of the fiber optic splitter / coupler 1, a reflector is provided on one side of the collimator, a focusing unit is provided on one side of the reflector, and a beam splitter is directly provided on the focusing unit and the reflector; the optical detection unit emits detection light, the detection light passes through fiber 2 and fiber optic splitter / coupler 1, enters fiber 3 and reaches a light exit point, the detection light exits from the light exit point and enters the collimator to form a collimated light beam, the collimated light beam passes through the reflector and the beam splitter to reach the focusing unit to form a final detection light focused on the processing surface.

[0008] Furthermore, after detecting the processed surface, the final detection light returns to the light exit point along the original path through the focusing unit, beam splitter, reflector, and collimator to form return detection light. The return detection light enters optical fiber one through optical fiber three and optical fiber splitter / coupler one to reach the spectrometer. The spectrometer receives the spectral signal and obtains the spectral frequency. The spectral frequency is used to convert it into the distance between the laser processing head and the processing surface.

[0009] Furthermore, when the laser processing unit is a fiber laser, the laser processing unit emits a laser beam, and a fiber splitter / coupler 1 is provided on one side of the laser processing unit, a collimator is provided on one side of the fiber splitter / coupler 1, and a focusing unit is provided on one side of the collimator; the laser beam enters the fiber 5 through the fiber 1 and the fiber splitter / coupler 1 and reaches the light output point, and the laser beam starts from the light output point, is collimated by the collimator and focused by the focusing unit to form a processing laser spot.

[0010] Furthermore, a fiber optic splitter / coupler 2 is provided on one side of the optical detection unit, and the fiber optic splitter / coupler 2 is connected to the fiber optic splitter / coupler 1; the optical detection unit emits detection light, the detection light passes through the fiber 3 and the fiber optic splitter / coupler 2 and enters the fiber 4, and then enters the fiber 5 through the fiber optic splitter / coupler 1 and reaches the light output point, the detection light is emitted from the light output point and enters the collimating mirror to form a collimated light beam, and the collimated light beam reaches the focusing unit to form the final detection light focused on the processing surface.

[0011] Furthermore, after detecting the processed surface, the final detection light returns to the light exit point along the original path through the focusing unit and the collimating mirror to form return detection light. The return detection light enters the optical fiber four through the optical fiber five and the optical fiber splitter / coupler one, and then reaches the optical fiber splitter / coupler two, enters the optical fiber two and reaches the spectrometer. The spectrometer receives the spectral signal and obtains the spectral frequency, which is used to convert into the distance between the laser processing head and the processing surface.

[0012] In traditional laser processing, it is necessary to introduce a fiber spectral confocal system; when using fiber lasers, the fiber spectral confocal system can be organically integrated with the processing fiber. Therefore, when different lasers are used, different structures are used.

[0013] The present invention also provides a control method for a follow-up laser processing device, using the follow-up laser processing device, and the control method is as follows:

[0014] Step 1, obtain the parameters of the processing position zero in the current detection area;

[0015] Step 2, control the laser processing head to scan up and down in the Z-axis direction, and receive the spectral signal through the spectrometer; normalize the spectral signal with the calibration curve to obtain the spectral frequency with the strongest reflected light intensity;

[0016] Step 3, converting the spectral frequency with the strongest reflected light intensity into the distance between the laser processing head and the processing surface;

[0017] Step 4, adjusting the position of the laser processing head in the Z-axis direction according to the distance between the laser processing head and the processing surface obtained in step 3;

[0018] Step 5: Repeat steps 3 and 4 until the processing is completed.

[0019] Furthermore, in step 2, the laser processing head is controlled to scan up and down in the Z-axis direction, and the spectral signal received by the spectrometer is normalized with the calibration curve to obtain the spectral frequency with the strongest reflected light intensity:

[0020] step , Place the object to be processed on a precision Z-axis platform, below the follow-up laser processing device, and control the Z-axis to move up and down precisely. Each time it moves to a certain position, record the original spectrum curve and the light intensity signal Ii of each spectrum point λi;

[0021] Step B, merging all the spectral curves obtained in step A into one chart, calculating the maximum light intensity signal at each spectral point λi, and obtaining a new curve, which is recorded as the calibration spectral curve;

[0022] Step C, compare all the original spectral curves obtained in step A and the light intensity signal Ii of each spectral point λi with the light intensity signal Ici of each spectral point λi of the calibrated spectral curve in step B to obtain a set of numerical redrawn images, thereby obtaining a normalized spectral curve at each moving position Zi and obtaining the spectral frequency with the strongest reflected light intensity.

[0023] Furthermore, in step 3, the spectral frequency with the strongest reflected light intensity is converted into the distance between the laser processing head and the processing surface, specifically:

[0024] Step I: for each normalized spectral curve at the moving position Zi, the spectral point λimax corresponding to the maximum light intensity can be obtained, and a position measurement calibration curve is drawn according to a set of (λimax, Zi);

[0025] Step II: Search the spectral point λmax corresponding to the maximum light intensity point from the position measurement calibration curve obtained in step I, and then obtain the corresponding position information according to the position measurement calibration curve, from which the distance between the laser processing head and the processing surface can be obtained.

[0026] Beneficial effects:

[0027] (1) The present invention breaks the original technical limitations by combining the laser processing unit, the optical detection unit and the distance measurement unit. It can be applied to a variety of materials such as glass, ceramics, silicon wafers, etc. for cutting or drilling, not limited to metal materials;

[0028] (2) The present invention can directly obtain the height information at the position through one measurement, and the measurement accuracy can reach micrometer or even sub-micrometer measurement accuracy, which fully matches the current laser focal depth parameters and achieves the best processing effect;

[0029] (3) The present invention can match the detection speed with the laser processing efficiency without the need for a high-speed precision motion platform. When the processing surface is outside the processing focus, the Z-axis controls the follower device to reach the processing focus, saving costs.

[0030] (4) In the present invention, the laser focusing of the processing part and the optical focusing part of the spectral confocal detection share a set of lenses, so that the processing and detection positions are consistent, and there is no need to adjust or compensate the relative positions. Only one calibration of the spectral confocal is required;

[0031] (5) The control system of the present invention realizes the coordinated control of the two systems, which can ensure the synchronization of detection and processing;

[0032] (6) In the present invention, due to the organic unity of control, time-sharing measurement and processing can be achieved during the processing, and since the measurement time of spectral confocal is very short, on the order of several ms, the impact on the processing is not significant; or simultaneous processing and measurement can be performed to directly eliminate interference signals and ensure the accuracy of the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural diagram of the present invention when the laser processing unit is a conventional laser;

[0034] Figure 2 is a schematic structural diagram of the present invention when the laser processing unit is a fiber laser;

[0035] Figure 3 is a flow chart of the control method of the present invention;

[0036] Figure 4 The relative placement positions of the follow-up laser processing device in Example 3, the object to be measured, and the precision Z-axis platform;

[0037] Figure 5~Figure 8 Spectral curves when the positions are Z1, Z2, Z3, and Z4 in Example 3;

[0038] Fig. 9 In Example 3, Figure 5~Figure 8 The spectral curves of are fitted together;

[0039] Figure 10~Figure 13 is the normalized spectrum curve when the position is Z1, Z2, Z3, and Z4 in Example 3;

[0040] Fig.14 is the position measurement calibration curve in Example 3;

[0041] Fig.15 A comparison of a set of measured spectral curves and a calibrated spectral curve obtained by time-sharing processing / measurement during the processing in Example 3;

[0042] Fig.16 For Example 3 Fig.15 After the measured spectrum curve is normalized, the spectrum point λmax corresponding to the maximum light intensity point is searched;

[0043] Fig.17 For Example 3 Fig.15 , obtain the corresponding position information according to the position measurement calibration curve;

[0044] Fig.18 A comparison of a set of measured spectral curves and a calibrated spectral curve obtained by synchronous processing / measurement during the processing in Example 3;

[0045] Fig.19 For Example 3 Fig.18 After the measured spectrum curve is normalized, the spectrum point λsub corresponding to the maximum light intensity point is searched;

[0046] Fig. 20 For Example 3 Fig.18 , the corresponding position information is obtained according to the position measurement calibration curve. DETAILED DESCRIPTION

[0047] The present invention will be further described below in conjunction with the accompanying drawings.

[0048] Example 1

[0049] When the laser processing unit is a conventional laser, the structural schematic diagram of the present invention is shown in FIG. Figure 1The present invention provides a follow-up laser processing device, comprising a laser processing unit 1 and an optical detection unit 2. The laser processing unit 1 is used to emit a laser beam and converge it into a processing laser spot. The optical detection unit 2 is used to emit detection light. After the detection light reaches the processing surface, it returns to the distance measuring unit. The distance measuring unit includes a spectrometer 3. The spectrometer 3 is used to measure the distance between the laser processing head and the processing surface. The laser processing unit 1 emits a laser beam. A beam expander 4 is provided on one side of the laser beam. A beam splitter 5 is provided on one side of the beam expander 4. A focusing unit 6 is provided on one side of the beam splitter 5. The laser beam is collimated by the beam expander 4 and then converged into a processing laser spot by the focusing unit 6. A fiber optic splitter / coupler 8 is provided on one side of the optical detection unit 2, a collimator 11 is provided on one side of the fiber optic splitter / coupler 8, a reflector 12 is provided on one side of the collimator 11, a focusing unit 6 is provided on one side of the reflector 12, and a beam splitter 5 is directly provided on the focusing unit 6 and the reflector 12; the optical detection unit 2 emits detection light, the detection light passes through the optical fiber 2 7 and the fiber optic splitter / coupler 8, enters the optical fiber 3 9 and reaches the light exit point 10, the detection light exits from the light exit point 10 and enters the collimator 11 to form a collimated light beam, the collimated light beam passes through the reflector 12 and the beam splitter 5 to reach the focusing unit 6 to form the final detection light focused on the processing surface. After detecting the processed surface, the final detection light returns to the light exit point 10 along the original path through the focusing unit 6, the beam splitter 5, the reflector 12, and the collimator 11 to form the return detection light. The return detection light enters the optical fiber 13 through the optical fiber three 9 and the optical fiber splitter / coupler 8 to reach the spectrometer 3. The spectrometer receives the spectral signal and obtains the spectral frequency. The spectral frequency is used to convert it into the distance between the laser processing head and the processing surface.

[0050] Example 2

[0051] When the laser processing unit 1 is a fiber laser, such as a spectrometer of Ocean Optics, model USB2000, the structural diagram of the present invention is shown in Figure 2The present invention provides a follow-up laser processing device, including a laser processing unit and an optical detection unit. The laser processing unit 1 is used to emit a laser beam and converge it into a processing laser spot. The optical detection unit 2 is used to emit detection light. After the detection light reaches the processing surface, it returns to the spectrometer 3. The spectrometer 3 is used to measure the distance between the laser processing head and the processing surface. The laser processing unit 1 emits a laser beam. A fiber splitter / coupler 8 is provided on one side of the laser processing unit 1. A collimator 11 is provided on one side of the fiber splitter / coupler 8. A focusing unit 6 is provided on one side of the collimator 11. The laser beam enters the optical fiber 5 16 through the optical fiber 13 and the optical fiber splitter / coupler 8 and reaches the light-emitting point 10. The laser beam starts from the light-emitting point 10, is collimated by the collimator 11, and converged by the focusing unit 6 into a processing laser spot. One side of the optical detection unit 2 is provided with a fiber splitter / coupler 2 15, and the fiber splitter / coupler 2 15 is connected to the fiber splitter / coupler 1 8; the optical detection unit 2 emits detection light, and the detection light passes through the fiber 3 9 and the fiber splitter / coupler 2 15 and enters the fiber 4 14, and then enters the fiber 5 16 through the fiber splitter / coupler 1 8 and reaches the light exit point 10, and the detection light exits from the light exit point 10 and enters the collimator 11 to form a collimated light beam, and the collimated light beam reaches the focusing unit 6 to form the final detection light focused on the processing surface. After the final detection light detects the processing surface, it returns to the light exit point 10 along the original path through the focusing unit 6 and the collimator 11 to form a return detection light, and the return detection light enters the fiber 4 14 through the fiber 5 16 and the fiber splitter / coupler 1 8, and then reaches the fiber splitter / coupler 2 15, enters the fiber 2 7 and reaches the spectrometer 3, and the spectrometer receives the spectrum signal to obtain the spectrum frequency, and the spectrum frequency is used to convert it into the distance between the laser processing head and the processing surface.

[0052] Example 3

[0053] The present invention provides a control method for a follow-up laser processing device, wherein the relative placement positions of the follow-up laser processing device I, the object to be measured II and the precision XYZ axis platform III are as follows: Figure 4 , Figure 4 The direction of the arrow in the middle is the moving direction of the X / Y / Z axis.

[0054] The follow-up laser processing device in Example 1 or Example 2 is used, and its control method is as follows:

[0055] Step 1: Before processing, at the starting point (X0, Y0), control the laser processing head to scan up and down in the Z-axis direction, and process a series of spectral signals received by the spectrometer to obtain a position calibration curve;

[0056] Step 2: Move the laser processing head in the Z-axis direction to the set position and start laser processing;

[0057] Step 3, move the X and Y axes to the next processing position, obtain a normalized spectrum curve based on the spectrum signal obtained by the spectrometer and the calibration spectrum curve, search for the spectrum frequency with the strongest reflected light intensity, and use the position calibration curve to convert it into the distance between the laser processing head and the processing surface;

[0058] Step 4: Adjust the position of the laser processing head in the Z-axis direction according to the distance between the laser processing head and the processing surface obtained in step 3.

[0059] Step 5: Repeat steps 3 and 4 until the processing is completed.

[0060] In step 1, the laser processing head is controlled to scan up and down in the Z-axis direction, and a series of spectral signals received by the spectrometer are processed to obtain a position calibration curve, specifically:

[0061] step , control the Z axis to move up and down precisely, and record the original spectrum curve and the light intensity signal Ii of each spectrum point λi every time it moves to a certain position; Figure 5~Figure 8 As shown, these are the spectral curves when the positions are Z1, Z2, Z3, and Z4, respectively.

[0062] Step B: combine all the spectral curves obtained in step A into one chart, calculate the maximum light intensity signal at each spectral point λi, and obtain a new curve, which is recorded as the calibration spectral curve; Fig. 9 As shown, Figure 5~Figure 8 The spectral curves of the two graphs are combined into one graph to obtain a new curve.

[0063] Step C: Compare all the original spectral curves obtained in step A and the light intensity signals Ii of each spectral point λi with the light intensity signals Ici of each spectral point λi of the calibrated spectral curve in step B to obtain a set of numerical redrawn images, thereby obtaining a normalized spectral curve at each moving position Zi and obtaining the spectral frequency with the strongest reflected light intensity. Figure 10~Figure 13 As shown, normalized spectral curves are obtained at positions Z1, Z2, Z3, and Z4, and the highest point in the figure is the spectral frequency with the strongest reflected light intensity at that position.

[0064] Step D: For each normalized spectral curve at the moving position Zi, the spectral point λi corresponding to the maximum light intensity can be obtained. According to a series of (λi, Zi), a position measurement calibration curve is drawn, which is: Fig.14 shown.

[0065] In step 3, the spectral signal obtained by the spectrometer is processed with the calibration spectral curve to obtain a normalized spectral curve, the spectral frequency with the strongest reflected light intensity is searched, and the position calibration curve is used to convert it into the distance between the laser processing head and the processing surface, specifically:

[0066] Step I: Obtain the actual spectrum curve during the processing and compare it with the calibration spectrum curve. Fig.15 As shown; the normalized spectrum curve is obtained, that is, Fig.16 shown.

[0067] Step II: Search the spectral point λmax corresponding to the maximum light intensity point from the normalized spectral curve obtained in step I, and then obtain the corresponding position information according to the position measurement calibration curve, that is, Fig.17 As shown, the distance between the laser processing head and the processing surface can be obtained from the position information. The spectrometer transmits the position information to the control device and controls the laser processing head to move according to the requirements.

[0068] In the present invention, the accuracy of measurement can also be ensured by eliminating interference signals. Since the wavelength λlaser of the light source spectrum reflected by the laser is known, there is a peak at the spectrum λlaser on the normalized spectrum curve. When calculating, the maximum value (normalized light intensity) other than λsub at this position can be searched first. If the maximum value (normalized light intensity) is greater than 0.8, the position corresponding to the position measurement calibration curve of λsub at this position is the height information, otherwise the position corresponding to the position measurement calibration curve of λlaser is the height information, see Fig.18 and Fig.19 .

[0069] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A control method for a follow-up laser processing device, the laser processing device comprising a laser processing unit (1) and an optical detection unit (2), the laser processing unit (1) being used to emit a laser beam and converge it into a processing laser spot, the optical detection unit (2) being used to emit detection light, the detection light reaching a processing surface and then returning to a distance measuring unit, the distance measuring unit comprising a spectrometer (3), the spectrometer (3) being used to measure the distance between a laser processing head and the processing surface; The laser processing unit (1) is a fiber laser. The laser processing unit (1) emits a laser beam. A fiber splitter / coupler (1) (8) is provided on one side of the laser processing unit (1). A collimator (11) is provided on one side of the fiber splitter / coupler (8). A focusing unit (6) is provided on one side of the collimator (11). The laser beam enters the fiber five (16) via the fiber one (13) and the fiber splitter / coupler (8) to reach the light exit point (10). The laser beam starts from the light exit point (10), is collimated by the collimator (11), and is focused by the focusing unit (6) to form a processing laser spot. A fiber splitter / coupler (15) (15) is provided on one side of the optical detection unit (2). The fiber splitter / coupler (15) (15) is connected to the fiber splitter / coupler (8). The optical detection unit (2) emits detection light. The detection light passes through the fiber three (9), The optical fiber splitter / coupler 2 (15) enters the optical fiber 4 (14), then enters the optical fiber 5 (16) through the optical fiber splitter / coupler 1 (8) and reaches the light exit point (10). The detection light exits the light exit point (10) and enters the collimator (11) to form a collimated light beam. The collimated light beam reaches the focusing unit (6) to form a final detection light focused on the processing surface. After the final detection light detects the processing surface, it returns to the light exit point (10) along the original path through the focusing unit (6) and the collimator (11) to form a return detection light. The return detection light enters the optical fiber 4 (14) through the optical fiber 5 (16) and the optical fiber splitter / coupler 1 (8), then reaches the optical fiber splitter / coupler 2 (15), enters the optical fiber 2 (7) and reaches the spectrometer (3). The spectrometer (3) receives the spectrum signal to obtain the spectrum frequency. The spectrum frequency is used to convert into the distance between the laser processing head and the processing surface. Features The control methods include: Step 1: Before processing, at the starting point (X0, Y0), control the laser processing head to scan up and down in the Z-axis direction, and process a series of spectral signals received by the spectrometer to obtain a position calibration curve; Step 2: Move the laser processing head in the Z-axis direction to the set position and start laser processing; Step 3, move the X and Y axes to the next processing position, obtain a normalized spectrum curve based on the spectrum signal obtained by the spectrometer and the calibration spectrum curve, search for the spectrum frequency with the strongest reflected light intensity, and use the position calibration curve to convert it into the distance between the laser processing head and the processing surface; Step 4, adjusting the position of the laser processing head in the Z-axis direction according to the distance between the laser processing head and the processing surface obtained in step 3; Step 5: Repeat steps 3 and 4 until the processing is completed; In step 1, the laser processing head is controlled to scan up and down in the Z-axis direction, and a series of spectral signals received by the spectrometer are processed to obtain a position calibration curve, specifically: step , control the Z axis to move up and down precisely, and record the original spectral curve and the light intensity signal Ii of each spectral point λi for each position moved; step B, merge all the spectral curves obtained in step A into a chart, calculate the maximum light intensity signal at each spectral point λi, and obtain a new curve, which is recorded as the calibration spectral curve; step C, compare all the original spectral curves and the light intensity signal Ii of each spectral point λi obtained in step A with the light intensity signal Ici of each spectral point λi of the calibration spectral curve in step B, and obtain a set of numerical redrawn images, thereby obtaining a normalized spectral curve at each moving position Zi, and obtaining the spectral frequency with the strongest reflected light intensity; Step D: for each normalized spectral curve at the moving position Zi, the spectral point λi corresponding to the maximum light intensity can be obtained, and a position measurement calibration curve is drawn according to a series of (λi, Zi); In step 3, the spectral signal obtained by the spectrometer is processed with the calibration spectral curve to obtain a normalized spectral curve, the spectral frequency with the strongest reflected light intensity is searched, and the position calibration curve is used to convert it into the distance between the laser processing head and the processing surface, specifically: Step I: obtaining an actual spectrum curve during the processing and comparing it with the calibration spectrum curve to obtain a normalized spectrum curve; Step II: Search the spectral point λmax corresponding to the maximum light intensity point from the normalized spectral curve obtained in step I, and then obtain the corresponding position information according to the position measurement calibration curve, from which the distance between the laser processing head and the processing surface can be obtained; the spectrometer transmits the position information to the control device and controls the laser processing head to move as required.

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