Method and system for material flatness characterization based on laser-induced breakdown spectroscopy

Abstract

The present application relates to the technical field of material flatness detection, and particularly relates to a material flatness characterization method and system based on laser-induced breakdown spectroscopy technology.The method comprises the following steps: S1, standard test: laser irradiation sampling operation is performed on a calibration sample, the distance is gradually quantitatively adjusted, and detection data at different distances are obtained; S2, calibration curve determination: a comparison characteristic parameter is selected, data values are extracted, and a calibration curve is prepared; and S3, flatness test: laser irradiation sampling operation is performed on a material to be detected, the comparison characteristic parameter of each test region is compared with the calibration curve, and local flatness information of the material to be detected is quantitatively determined.The present application can quantitatively determine the local flatness information of the material to be detected without contact, has high test efficiency, has low requirement on the technical level of an operator, has small limitation, and has the functions of in-situ and rapid quantitative characterization of material flatness.

Description

Technical Field

[0001] This invention relates to the field of material flatness testing technology, and in particular to a material flatness characterization method and system based on laser-induced breakdown spectroscopy. Background Technology

[0002] Flatness of a material refers to the deviation of the unevenness of a local surface from an ideal plane; it is what we usually refer to as the flatness of a local surface. The characterization of material flatness has a wide range of applications in fields such as precision component assembly and precision machining. For example, in component assembly, flatness directly affects the overall performance of the machine; in machining, flatness is a key quality indicator for evaluating machining processes.

[0003] Currently, most quantitative characterization methods for flatness are contact-based measurement schemes, such as feeler gauge measurement, liquid level method, level measurement, and dial indicator measurement. Before formal measurement, these methods typically involve placing the material to be measured on a dedicated sample platform and then determining the ideal surface and measurement area distribution scheme through detailed analysis of the material's configuration. These characterization methods generally suffer from drawbacks such as low efficiency, high skill requirements for operators, and limited selectable measurement areas on the material surface, lacking the capability for in-situ, rapid, and quantitative characterization of material flatness. Summary of the Invention

[0004] To address the technical problems that current quantitative characterization methods for flatness mostly rely on contact measurement schemes, which require high levels of technical expertise from operators and have limited selectable measurement areas on the material surface, this invention provides a material flatness characterization method and system based on laser-induced breakdown spectroscopy.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A material flatness characterization method based on laser-induced breakdown spectroscopy, characterized in that it is used to quantitatively characterize the flatness of the material under test, the method comprising:

[0007] S1. Standard test: Prepare a calibration sample with the same material as the material to be tested and a smooth end face. Perform laser irradiation sampling on the calibration sample using laser-induced breakdown spectroscopy. Gradually and quantitatively adjust the distance between the calibration sample and the laser irradiation device to obtain the test data of the calibration sample at different distances from the laser irradiation device.

[0008] S2. Calibration curve determination: Select spectral feature parameters that have a one-to-one correspondence between data values ​​and the distance between calibration samples and laser irradiation equipment as comparison feature parameters, extract the comparison feature parameter data values ​​from the detection data at different distances, and use the distance between calibration samples and laser irradiation equipment and the spectral feature parameter data values ​​as the horizontal and vertical axes to obtain the calibration curve.

[0009] S3. Flatness Test: Using the test parameters in the standard test, laser irradiation sampling is performed on each test area of ​​the material to be tested. The comparative characteristic parameters of each test area are compared with the calibration curve to quantify the local flatness information of the material to be tested.

[0010] Furthermore, the laser irradiation equipment uses a vertical incidence method to perform focused pulsed laser beam irradiation detection on the calibration sample and the material to be tested.

[0011] Furthermore, the focal plane of the laser beam generated by the laser irradiation device is positioned behind the target sample and the material to be tested.

[0012] Furthermore, in step S1, the laser irradiation sampling operation performed on the calibration sample using laser-induced breakdown spectroscopy, and the gradual quantitative adjustment of the distance between the calibration sample and the laser irradiation device to obtain the detection data of the calibration sample at different distances from the laser irradiation device, includes:

[0013] The calibration sample is placed on a precisely and continuously adjustable three-dimensional moving platform;

[0014] The pulsed laser beam provided by the laser irradiation equipment is focused by a lens and then irradiated onto the upper surface of the calibration sample. Plasma is generated through laser ablation, and the LIBS spectrum caused by a single laser pulse is collected to obtain the detection data.

[0015] The sample platform is moved in a set step size so that the distance from the upper surface of the calibration sample to the focal plane gradually increases relative to the pre-set initial distance, and detection data at different distances are collected.

[0016] Furthermore, in step S2, the comparison feature parameters include the intensity / width of the feature spectral line corresponding to a single element, or the intensity ratio of two feature spectral lines.

[0017] Furthermore, in step S2, the calibration curve is established with the distance from the focal plane to the upper surface of the calibration sample as the abscissa and the value of the intensity of the characteristic spectral lines or the intensity ratio of the characteristic spectral lines as the ordinate.

[0018] Furthermore, step S3 specifically includes:

[0019] The equipment parameters used when constructing the calibration curve are fixed;

[0020] The selected measurement areas on the surface of the material to be tested are tested step by step using a laser irradiation device. The generated laser plasma emission spectrum is collected to obtain the test data of each measurement area of ​​the material to be tested.

[0021] The comparison feature parameters are extracted from the test data of each measurement area of ​​the material to be tested. The comparison feature parameter data values ​​of each measurement area are compared with the calibration curve to quantify the local flatness information of the material to be tested.

[0022] Furthermore, in step S3, the test parameters in the standard test include the relative position between the laser irradiation device and the calibration sample, laser parameters, and spectral acquisition parameters.

[0023] On the other hand, the present invention also provides a material flatness characterization system based on laser-induced breakdown spectroscopy, including a laser radiation device and a data acquisition device; the laser radiation device is used to provide a pulsed laser beam for testing, and the data acquisition device is used to acquire the spectra of calibration samples and materials under test after testing to obtain test data; the system executes the above-mentioned material flatness characterization method based on laser-induced breakdown spectroscopy through the laser radiation device and the data acquisition device.

[0024] Furthermore, it also includes a three-dimensional moving platform, which is used to carry the calibration sample and can quantitatively adjust the distance between the laser radiation device and the calibration sample.

[0025] This invention utilizes laser-induced breakdown spectroscopy (LAS) to sample calibration samples with the same material and smooth end faces as the material under test. By measuring the calibration samples at different distances, parameters related to the test distance are extracted and a calibration curve is generated. This calibration curve serves as a characterization curve for the material's flatness, quantifying the local flatness information of the material under test. This method can quantify the local flatness information of the material under test without contact, offering high testing efficiency, low skill requirements for operators, and minimal limitations. It provides in-situ, rapid, and quantitative characterization of material flatness. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the material flatness characterization method based on laser-induced breakdown spectroscopy in an embodiment of the present invention.

[0027] Figure 2 This invention provides a calibration curve for comparing characteristic parameters using the characteristic spectral lines corresponding to a single element, as shown in the embodiment of the invention. Figure 1 .

[0028] Figure 3 This invention provides a calibration curve for comparing characteristic parameters using the characteristic spectral lines corresponding to a single element, as shown in the embodiment of the invention. Figure 2 .

[0029] Figure 4 This is a calibration curve diagram of the characteristic parameters, which is a comparison of the intensity ratio of two characteristic spectral lines, according to an embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] In the accompanying drawings of the embodiments of this application, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper", "lower", "left", "right", "top", "bottom", "inner", "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this patent.

[0032] Furthermore, if terms such as "first" or "second" are used for descriptive purposes only, they are mainly used to distinguish different devices, components or parts (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance or quantity of the indicated devices, components or parts, and should not be construed as indicating or implying relative importance.

[0033] Example 1

[0034] Figure 1 This is a flowchart illustrating the material flatness characterization method based on laser-induced breakdown spectroscopy in an embodiment of the present invention.

[0035] This embodiment provides a material flatness characterization method based on laser-induced breakdown spectroscopy (LIBS). This method uses LIBS to quantitatively characterize the flatness of the material under test. LIBS, as an emerging material surface chemical composition analysis technique, features in-situ and rapid analysis, and has broad application prospects in industrial process monitoring. LIBS utilizes a focused pulsed laser to ablate a localized area of ​​the material surface, generating micro-plasma. The quantitative analysis of the material surface chemical composition is achieved by measuring the emission spectrum of the micro-plasma. The area ablated by the pulsed laser is typically tens to hundreds of micrometers in size. Since LIBS involves only optical contact at the micrometer scale during the entire analysis process, its selection of the analysis area is almost unrestricted by the macroscopic shape of the material, and it also exhibits high position-resolution surface analysis capabilities.

[0036] Since the state of the micro-plasma generated by LIBS technology is affected by the surface flatness of the analysis area, i.e., the laser-irradiated area, there is a correlation between the emission spectrum characteristics of the plasma and the local flatness of the material. Therefore, this embodiment extends the high position resolution LIBS technology to in-situ, rapid characterization of material flatness by defining a spectral probe that can sensitively characterize the flatness of the material.

[0037] Based on LIBS technology, this embodiment uses a calibration curve to characterize the flatness of the material under test by performing standard tests on calibration samples with the same material and smooth end faces as the material to be tested. Specifically, as shown... Figure 1 As shown, the method specifically includes:

[0038] S1. Standard Test: Prepare a calibration sample with the same material as the material to be tested and a smooth end face. Perform laser irradiation sampling on the calibration sample using laser-induced breakdown spectroscopy. Gradually and quantitatively adjust the distance between the calibration sample and the laser irradiation device to obtain the test data of the calibration sample at different distances from the laser irradiation device.

[0039] The calibration sample serves as an ideal sample and acts as a comparison sample for the material to be tested. The detection data obtained by laser irradiation operation of the calibration sample at different distances can be used as comparison data for the material to be tested to characterize the flatness between various local areas of the material to be tested.

[0040] During the testing process, after the calibration sample is fixed, the focused pulsed laser provided by the laser irradiation equipment irradiates the upper surface of the calibration sample to generate plasma. The acquisition device collects the emission spectrum of the generated plasma, which serves as the detection data of the calibration sample at that distance. The position of the calibration sample is quantitatively adjusted, and the laser beam irradiation-acquisition operation is repeated to obtain the detection data of the calibration sample at multiple distance segments. Here, distance refers to the distance between the calibration sample and the laser irradiation equipment. Of course, since the positions of the laser irradiation equipment and the focusing lens remain unchanged during the detection process, the distance can also be the distance between the calibration sample and the focal plane.

[0041] S2. Calibration curve determination: Select spectral feature parameters that have a one-to-one correspondence between data values ​​and the distance between calibration samples and laser irradiation equipment as comparison feature parameters, extract the comparison feature parameter data values ​​from the detection data at different distances, and use the distance between calibration samples and laser irradiation equipment and the spectral feature parameter data values ​​as the horizontal and vertical axes to obtain the calibration curve.

[0042] Since this method is used to characterize material flatness—that is, to characterize material flatness by comparing the detection data of calibration samples at different distances—the selection of comparison feature parameters needs to have an observable correlation with the distance from the laser irradiation device / focal plane to the upper surface of the calibration sample. For example, spectral feature parameters whose values ​​gradually decrease as the test distance of the calibration sample increases can be used as comparison feature parameters. Correspondingly, the comparison feature parameters can also be the intensity ratio of two characteristic spectral lines, rather than being limited to the spectral feature parameters of a single element.

[0043] When developing the calibration curve, the horizontal and vertical axes are selected from the test distance of the calibration sample and the comparison feature parameter data value, respectively, to clearly show the relationship between the test distance and the comparison feature parameter data value.

[0044] S3. Flatness Test: Using the test parameters in the standard test, laser irradiation sampling is performed on each test area of ​​the material to be tested. The comparative characteristic parameters of each test area are compared with the calibration curve to quantify the local flatness information of the material to be tested.

[0045] During the testing of the material under test, all test parameters should remain consistent with those used in standard testing to control variables and ensure the reliability of the comparison. Test parameters include the position of the laser irradiation device / focal plane, laser irradiation intensity, and spectral acquisition parameters. Specifically, the calibration sample is replaced with the material under test in the standard testing process. The distance between the material under test and the laser irradiation device can be selected from the intermediate distance value used in the calibration sample test to ensure that all uneven areas of the material under test can be characterized.

[0046] Preferably, the laser irradiation equipment uses a vertically incident focused pulsed laser beam to irradiate and test the calibration sample and the material to be tested. This facilitates the quantitative adjustment of the distance to the calibration sample and the calculation of the flatness of the material to be tested. Also preferably, the focal plane of the laser beam generated by the laser irradiation equipment is set behind the calibration sample and the material to be tested.

[0047] The advantage of this embodiment is that the material flatness characterization method extracts parameters related to the test distance of calibration samples by sampling and testing calibration samples at different distances, and generates a calibration curve. This calibration curve is then used as the characterization curve for material flatness, quantifying the local flatness information of the material under test. This method can quantify the local flatness information of the material under test without contact, has high testing efficiency, low requirements for operator skill level, and few limitations, and possesses the function of in-situ, rapid, and quantitative characterization of material flatness.

[0048] Example 2

[0049] This embodiment also discloses a material flatness characterization method based on laser-induced breakdown spectroscopy. The difference from Embodiment 1 is that this embodiment also provides some implementation methods.

[0050] In this embodiment, preferably, in step S1, the calibration sample is subjected to laser irradiation sampling using laser-induced breakdown spectroscopy, and the distance between the calibration sample and the laser irradiation device is gradually and quantitatively adjusted to obtain detection data of the calibration sample at different distances from the laser irradiation device, including:

[0051] The calibration sample is placed on a precisely and continuously adjustable three-dimensional moving platform;

[0052] The pulsed laser beam provided by the laser irradiation equipment is focused by a lens and then irradiated onto the upper surface of the calibration sample. Plasma is generated through laser ablation, and the LIBS spectrum caused by a single laser pulse is collected to obtain the detection data.

[0053] The sample platform is moved in a set step size so that the distance from the upper surface of the calibration sample to the focal plane gradually increases relative to the pre-set initial distance, and detection data at different distances are collected.

[0054] The three-dimensional moving platform is positioned relative to the laser beam provided by the laser irradiation equipment. The calibration sample is fixed on the three-dimensional moving platform, and the distance between the sample and the laser irradiation equipment is quantitatively adjusted through the three-dimensional moving platform.

[0055] Preferably, in step S2, the comparison feature parameters include, but are not limited to, the intensity / width of a feature spectral line corresponding to a single element, or the intensity ratio of two feature spectral lines. Also preferably, the calibration curve is constructed with the distance from the focal plane to the upper surface of the calibration sample as the abscissa and the numerical value of the feature spectral line intensity or the intensity ratio of the feature spectral lines as the ordinate.

[0056] Preferably, step S3 specifically includes:

[0057] The equipment parameters used when constructing the calibration curve are fixed;

[0058] The selected measurement areas on the surface of the material to be tested are tested step by step using a laser irradiation device. The generated laser plasma emission spectrum is collected to obtain the test data of each measurement area of ​​the material to be tested.

[0059] The comparison feature parameters are extracted from the test data of each measurement area of ​​the material to be tested. The comparison feature parameter data values ​​of each measurement area are compared with the calibration curve to quantify the local flatness information of the material to be tested.

[0060] The equipment parameters include the relative position between the laser irradiation equipment and the calibration sample, laser parameters, and spectral acquisition parameters. The material under test is adjusted by translation to receive laser radiation from the laser beam in each measurement area. After obtaining the test data for each measurement area of ​​the material under test, the comparative characteristic parameter data values ​​of each measurement area are compared with the calibration curve. For example, if the comparative characteristic parameter data values ​​for two measurement areas of the material under test are A and B, and data values ​​A and B are 5.0 mm and 5.2 mm respectively in the calibration curve, it can be determined that the test area with data value A is relatively convex relative to the test area with data value B, and the planar distance differs by 0.2 mm.

[0061] To provide a better user experience, a specific implementation method of this embodiment is provided.

[0062] In this embodiment, the material to be tested is alloy steel.

[0063] An alloy steel material purchased from the China National Standard Material Network was selected as the calibration sample to illustrate this invention. The selected calibration sample has a uniform and known chemical composition, is cylindrical in shape, has a base diameter of 30 mm, a height of 26 mm, and a flatness of better than 50 micrometers at both ends.

[0064] In standard testing, the calibration sample is placed on a precisely and continuously adjustable three-dimensional moving platform. A pulsed laser beam from the LIBS system, after passing through a focusing lens, is perpendicularly irradiated onto the upper surface of the calibration sample, generating plasma through laser ablation. The laser pulse energy is set to a constant value, and the initial position of the irradiated calibration sample end face is set several millimeters in front of the focal plane. The corresponding laser spot on the calibration sample end face can be set within the range of tens or hundreds of micrometers. The start time of the plasma emission spectrum acquisition time gate is delayed by hundreds of nanoseconds or several microseconds relative to the laser pulse. During spectral acquisition, the sample stage is positioned on a plane perpendicular to the laser beam and performs scanning translation.

[0065] The sample stage is moved in a step size parallel to the laser transmission direction, so that the distance from the upper surface of the calibration sample to the focal plane gradually increases from the pre-set initial position, which simulates different flatness conditions. Under each simulated flatness condition, LIBS spectra caused by several single laser pulses are collected to obtain the detection data of the calibration sample at different positions.

[0066] In determining the calibration curve, for each simulated flatness case, i.e. the detection data of the calibration sample at different positions, the same number of single laser pulse LIBS spectra are superimposed. Taking the two spectral lines Fe II 322.79nm and Fe I 404.58nm as examples, the emission intensity information of the characteristic spectral lines is extracted.

[0067] Using the distance from the focal plane to the top surface of the calibration sample as the horizontal axis, and the emission intensity of the selected spectral line and the emission intensity ratio of the selected spectral line as the vertical axes, a calibration curve is established between flatness and specific spectral line parameters. For details, please refer to [reference needed]. Figure 2-4 .in, Figure 2 The Fe II 322.79nm was used as the comparison characteristic parameter. Figure 3 Therefore Figure 4 Fe I 404.58nm was used as the comparison feature parameter, while Figure 4 The intensity ratio of Fe II (322.79 nm) and Fe I (404.58 nm) was used as the comparison characteristic parameter.

[0068] The calibration curves show a clear correlation between the flatness simulated using calibrated samples and the spectral parameters. Specifically, the three specific spectral parameters and the flatness all exhibit a monotonic, near-linear relationship, suggesting that this implementation can achieve a high-precision quantitative characterization of flatness.

[0069] In the flatness test, the equipment parameters used to construct the calibration curve are fixed, and the laser plasma emission spectra generated at each selected measurement area on the surface of the material to be tested are measured step by step based on these parameters to obtain the corresponding spectral parameters.

[0070] By comparing the spectral parameters corresponding to each selected measurement area with the established calibration curve, the local flatness information of the material to be tested can be quantitatively determined.

[0071] Example 3

[0072] This embodiment discloses a material flatness characterization system based on laser-induced breakdown spectroscopy (LAS). The system includes a laser radiation device and a data acquisition device. The laser radiation device provides a pulsed laser beam for testing, and the data acquisition device acquires the spectra of calibration samples and the material under test after testing, obtaining test data. The system, through the laser radiation device and the data acquisition device, executes a material flatness characterization method based on LAS, which includes:

[0073] S1. Standard test: Prepare a calibration sample with the same material as the material to be tested and a smooth end face. Perform laser irradiation sampling on the calibration sample using laser-induced breakdown spectroscopy. Gradually and quantitatively adjust the distance between the calibration sample and the laser irradiation device to obtain the test data of the calibration sample at different distances from the laser irradiation device.

[0074] S2. Calibration curve determination: Select spectral feature parameters that are positively correlated with the distance between the data value and the calibration sample and the laser irradiation device as comparison feature parameters. Extract the comparison feature parameter data values ​​from the detection data at different distances. Use the distance between the calibration sample and the laser irradiation device and the spectral feature parameter data values ​​as the horizontal and vertical axes to obtain the calibration curve.

[0075] S3. Flatness Test: Using the test parameters in the standard test, laser irradiation sampling is performed on each test area of ​​the material to be tested. The comparative characteristic parameters of each test area are compared with the calibration curve to quantify the local flatness information of the material to be tested.

[0076] Specifically, the material flatness characterization method based on laser-induced breakdown spectroscopy in this embodiment adopts the method in Embodiment 1 or Embodiment 2.

[0077] Preferably, the material flatness characterization system further includes a three-dimensional moving platform, which is used to carry the calibration sample and can quantitatively adjust the distance between the laser radiation device and the calibration sample.

[0078] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for characterizing the flatness of materials based on laser-induced breakdown spectroscopy, characterized in that, The method for quantitatively characterizing the flatness of a material to be tested includes: S1. Standard test: Prepare a calibration sample with the same material as the material to be tested and a smooth end face. Perform laser irradiation sampling on the calibration sample using laser-induced breakdown spectroscopy. Gradually and quantitatively adjust the distance between the calibration sample and the laser irradiation device to obtain the test data of the calibration sample at different distances from the laser irradiation device. S2. Calibration curve determination: Select spectral feature parameters that have a one-to-one correspondence between data values ​​and the distance between calibration samples and laser irradiation equipment as comparison feature parameters, extract the comparison feature parameter data values ​​from the detection data at different distances, and use the distance between calibration samples and laser irradiation equipment and the spectral feature parameter data values ​​as the horizontal and vertical axes to obtain the calibration curve. S3. Flatness Test: Using the test parameters in the standard test, laser irradiation sampling is performed on each test area of ​​the material to be tested. The comparative characteristic parameters of each test area are compared with the calibration curve to quantify the local flatness information of the material to be tested.

2. The material flatness characterization method based on laser-induced breakdown spectroscopy as described in claim 1, characterized in that, The laser irradiation equipment uses a vertical incidence method to irradiate the calibration sample and the material to be tested with a focused pulsed laser beam.

3. The material flatness characterization method based on laser-induced breakdown spectroscopy as described in claim 1, characterized in that, The focal plane of the laser beam generated by the laser irradiation device is positioned behind the target sample and the material to be tested.

4. The material flatness characterization method based on laser-induced breakdown spectroscopy as described in claim 1, characterized in that, In step S1, the laser irradiation sampling operation of the calibration sample using laser-induced breakdown spectroscopy, and the gradual quantitative adjustment of the distance between the calibration sample and the laser irradiation device to obtain the detection data of the calibration sample at different distances from the laser irradiation device, includes: The calibration sample is placed on a precisely and continuously adjustable three-dimensional moving platform; The pulsed laser beam provided by the laser irradiation equipment is focused by a lens and then irradiated onto the upper surface of the calibration sample. Plasma is generated through laser ablation, and the LIBS spectrum caused by a single laser pulse is collected to obtain the detection data. The sample platform is moved in a set step size so that the distance from the upper surface of the calibration sample to the focal plane gradually increases relative to the pre-set initial distance, and detection data at different distances are collected.

5. The material flatness characterization method based on laser-induced breakdown spectroscopy according to claim 1, characterized in that, In step S2, the comparison feature parameters include the intensity / width of the feature spectral line corresponding to a single element, or the intensity ratio of two feature spectral lines.

6. The material flatness characterization method based on laser-induced breakdown spectroscopy as described in claim 5, characterized in that, In step S2, the calibration curve is established with the distance from the focal plane to the upper surface of the calibration sample as the abscissa and the intensity of the characteristic spectral lines or the intensity ratio of the characteristic spectral lines as the ordinate.

7. The material flatness characterization method based on laser-induced breakdown spectroscopy as described in claim 1, characterized in that, Step S3 specifically includes: The equipment parameters used when constructing the calibration curve are fixed; The selected measurement areas on the surface of the material to be tested are tested step by step using a laser irradiation device. The generated laser plasma emission spectrum is collected to obtain the test data of each measurement area of ​​the material to be tested. The comparison feature parameters are extracted from the test data of each measurement area of ​​the material to be tested. The comparison feature parameter data values ​​of each measurement area are compared with the calibration curve to quantify the local flatness information of the material to be tested.

8. The material flatness characterization method based on laser-induced breakdown spectroscopy according to claim 1, characterized in that, In step S3, the test parameters in the standard test include the relative position between the laser irradiation device and the calibration sample, laser parameters, and spectral acquisition parameters.

9. A material flatness characterization system based on laser-induced breakdown spectroscopy, characterized in that, The system includes a laser radiation device and a data acquisition device; the laser radiation device is used to provide a pulsed laser beam for testing, and the data acquisition device is used to acquire the spectra of calibration samples and materials under test after testing, thereby obtaining test data; the system uses the laser radiation device and the data acquisition device to perform the material flatness characterization method based on laser-induced breakdown spectroscopy as described in any one of claims 1-8.

10. The material flatness characterization system based on laser-induced breakdown spectroscopy according to claim 9, characterized in that, It also includes a three-dimensional moving platform, which is used to carry the calibration sample and can quantitatively adjust the distance between the laser radiation device and the calibration sample.

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