Solid sample testing method based on laser-induced breakdown spectroscopy

Abstract

The invention discloses a solid sample testing method based on laser-induced breakdown spectroscopy, which specifically comprises the following steps: (1) forming a solid sample group by using a solid sample to be tested and a first standard solid sample, and forming a solid sample group by using the solid sample to be tested and a second standard solid sample; (2) the laser-induced breakdown spectroscopy device collects LIBS spectral data of the two solid sample groups under the same experimental factor; (3) extracting the spectral intensity from the LIBS spectrums of the two solid sample groups, and further calculating the element mass fraction of the sample to be detected; the mass fraction of a to-be-detected element of the first standard solid sample is different from that of a to-be-detected element of the second standard solid sample. According to the method, mixed sample preparation of the standard solid sample and the to-be-detected solid sample is not needed, the standard addition method can be applied to the solid sample to realize detection of the mass fraction of the to-be-detected element in the solid sample, the standard addition method has remarkable advantages in overcoming the matrix effect, and the quantitative analysis accuracy of the to-be-detected solid sample is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sample testing, and more specifically, the present invention relates to a solid sample testing method based on laser induced breakdown spectroscopy. Background Art

[0002] In recent years, laser-induced breakdown spectroscopy (LIBS) based on plasma emission spectroscopy can perform qualitative and quantitative analysis on samples of various forms due to its portable instrument, real-time and rapid, and simultaneous analysis of multiple elements. Its quantitative analysis is to detect a set of standard samples with different concentrations and obtain a set of data results to compare with the test results of the sample to be tested to determine whether the sample to be tested is within a certain range. However, since it is impossible to obtain standard samples consistent with their matrix for solids such as metals, ceramics, and plastics, the quantitative analysis accuracy of LIBS still needs to be further improved.

[0003] The standard addition method can overcome the difficulty of preparing standard complex matrix samples and realize the correction of matrix effects. However, the conventional implementation method of the standard addition method is mainly to mix the standard sample with the sample to be tested. The specific implementation methods include: 1) adding standard samples with different concentration gradients of the element to be tested to the sample to be tested; 2) adding standard samples with different masses and fixed concentrations of the element to be tested to the sample to be tested; 3) adding standard samples with different volumes and fixed concentrations of the element to be tested to the sample to be tested. Using the above implementation methods, a calibration curve is established between the element concentration or volume or mass of the added standard sample and the spectral intensity of the element to be tested in the mixed sample, and the concentration of the element to be tested in the sample to be tested is converted by the intercept and slope of the calibration curve.

[0004] Since solid samples cannot be mixed with standard samples and samples to be tested, this method is currently only applicable to liquid or powder samples. Summary of the invention

[0005] The present invention provides a solid sample testing method based on laser induced breakdown spectroscopy, aiming to improve the above problems.

[0006] The present invention is implemented as follows: a method for testing solid samples based on laser induced breakdown spectroscopy, the method is specifically as follows:

[0007] (1) The solid sample to be tested and the first standard solid sample form a solid sample group, and the solid sample to be tested and the second standard solid sample form a solid sample group;

[0008] (2) The laser-induced breakdown spectroscopy device collected LIBS spectral data of two solid sample groups under the same experimental factors;

[0009] (3) The spectral intensities extracted from the LIBS spectra of the two solid sample groups are then used to calculate the elemental mass fractions of the samples to be tested;

[0010] The mass fraction of the element to be measured in the first standard solid sample is different from the mass fraction of the element to be measured in the second standard solid sample.

[0011] Furthermore, the mass fraction of the element to be tested in the sample to be tested C x The calculation formula is as follows:

[0012]

[0013] Wherein, I1 and I2 are the spectral intensities in the LIBS spectral data of the solid sample group where the first standard solid sample is located and the solid sample group where the second standard solid sample is located, respectively; C s1 , C s2 are the mass fractions of the elements to be measured in the first standard solid sample and the second standard solid sample respectively.

[0014] Furthermore, the determination method of the standard solid sample is as follows:

[0015] (11) collecting a LIBS spectrum of the solid sample to be tested, and determining the elements present in the solid sample to be tested based on the LIBS spectrum;

[0016] (12) determining the major element in the solid sample to be tested, and extracting the characteristic spectral line of the major element from the LIBS spectrum of the solid sample to be tested;

[0017] (13) screening solid samples as samples, taking characteristic spectral lines of all major elements in the solid samples as sample features, and using the mass fractions of the corresponding major elements in the solid samples as sample labels;

[0018] (14) constructing a spectral classification model based on the sample, inputting the characteristic spectral lines of each major element in the solid sample to be tested into the spectral classification model, and the spectral classification model outputs a predicted value of the mass fraction of each major element in the solid sample to be tested;

[0019] (15) Select two standard solid samples that have the same major element as the solid sample to be tested and have a similar mass fraction of the major element from the solid samples that meet the requirements of the standard addition method.

[0020] Furthermore, when the energy density of the laser pulses focused on the two groups of solid samples is the same, and the laser pulses focused on the two solid samples in each group of solid samples arrive at the same time, it is determined that the experimental factors of the two solid sample groups are the same.

[0021] Furthermore, the laser induced breakdown spectroscopy device comprises:

[0022] Laser, the laser beam emitted by the laser enters the beam splitter, and the beam splitter splits the laser beam into a transmitted laser beam and a reflected laser beam with inconsistent propagation directions;

[0023] The reflected laser beam is incident on the first reflecting mirror, and after being turned 90 degrees, the reflected laser beam is incident on the laser energy attenuator along the emission direction of the laser. After being attenuated by the laser energy attenuator, the reflected laser beam enters the laser energy detector. The energy of the attenuated reflected laser beam is detected by the first laser energy detector and then input into the first plano-convex lens. The first plano-convex lens focuses on the surface of the solid sample to be tested or the standard solid sample, and ablates the surface of the solid sample to be tested or the standard solid sample to generate plasma. The light generated by the energy level transition of the generated plasma will be coupled to one end of the Y-type quartz optical fiber by the first collection head;

[0024] The transmitted laser beam is incident on the second reflector at an incident angle of 45° and then emitted perpendicularly to the laser emission direction. It is then incident on the third reflector at an incident angle of 45° and then emitted into the second laser energy detector along the laser emission direction. The energy of the attenuated transmitted laser beam is detected by the second laser energy detector and then input into the second plano-convex lens. It is then input into the surface of the solid sample to be tested or the standard solid sample through the second plano-convex lens, and the surface of the solid sample to be tested or the standard solid sample is ablated to generate plasma. The light generated by the energy level transition of the generated plasma is coupled to the other end of the Y-type quartz optical fiber by the second collection head.

[0025] The light in the Y-shaped quartz optical fiber is transmitted through the spectral slit to the spectral detection device, and the spectral detection device detects the LIBS spectrum of light generated by the energy level transition of the plasma; the laser and the spectral detection device are connected through a BNC line. After the laser emits the laser, the signal of the laser beam emitted by the laser is synchronously transmitted to the spectral detection device through the BNC line. The spectral detection device collects the LIBS spectrum data of the light generated by the energy level transition of the plasma after a set time delay.

[0026] Furthermore, the laser energy attenuator is adjusted so that the energy of the attenuated reflected laser beam detected by the first laser energy detector is the same as the energy of the transmitted laser beam detected by the second laser energy detector.

[0027] Furthermore, the distance between the first plano-convex lens and the second plano-convex lens and the surface of the solid sample is adjusted to be the focal length of the plano-convex lens.

[0028] Furthermore, the optical paths of the transmitted laser beam and the reflected laser beam reaching the surface of the solid sample are controlled to be the same.

[0029] Furthermore, the first plano-convex lens and the second plano-convex lens can be moved forward and backward along the propagation direction of the laser beam to adjust the distance between the plano-convex lens and the surface of the solid sample.

[0030] The solid sample testing system based on laser induced breakdown spectroscopy provided by the present invention has the following features:

[0031] Beneficial effects:

[0032] (1) The laser-induced breakdown spectrum is consistent, which can ensure that the standard solid sample and the solid sample to be tested are ablated at the same time and with the same energy density, and ensure that the plasma collection efficiency of the standard solid sample and the solid sample to be tested is consistent;

[0033] (2) There is no need to prepare a mixed sample of the standard solid sample and the solid sample to be tested. The standard addition method can be used for the solid sample to detect the mass fraction of the element to be tested in the solid sample. The standard addition method has a significant advantage in overcoming the matrix effect and improves the accuracy of quantitative analysis of the solid sample to be tested.

[0034] (3) Only two standard solid samples are needed to achieve accurate quantitative analysis of solid samples by LIBS. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A flow chart of a solid sample testing method based on laser induced breakdown spectroscopy provided in an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of the optical path of a laser induced breakdown spectroscopy device provided in an embodiment of the present invention;

[0037] 1. Laser, 2. Beam splitter, 31. First reflector, 32. Second reflector, 33. Third reflector, 4. Laser energy attenuator, 51. First laser energy detector, 52. Second laser energy detector, 61. First plano-convex lens, 62. Second plano-convex lens, 7. Plasma, 8. Solid sample to be tested, 91. First collection head, 92. Second collection head, 10. Y-type quartz optical fiber, 11. Standard solid sample, 12. Displacement platform, 13. Spectrometer slit, 14. Spectral detection device, 15. Computer, 16. BNC line. Implementation

[0039] The specific implementation modes of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0040] Figure 1 A flow chart of a solid sample testing method based on laser induced breakdown spectroscopy provided in an embodiment of the present invention, the method comprising the following steps:

[0041] (1) The solid sample to be tested and the first standard solid sample form a solid sample group, and the solid sample to be tested and the second standard solid sample form a solid sample group;

[0042] In an embodiment of the present invention, LIBS spectrum data of a solid sample to be tested is obtained, and two standard solid samples with a matrix similar to that of the solid sample to be tested are obtained as a first standard solid sample and a second standard solid sample, respectively.

[0043] In the embodiment of the present invention, the selection process of the standard solid sample is as follows:

[0044] (11) Determining the elements present in the solid sample to be tested: First, collect the laser induced breakdown spectrum (LIBS) of the solid sample to be tested for qualitative analysis, and compare the collected LIBS spectrum data with the element emission line database of the National Institute of Standards and Technology (NIST) of the United States to further determine the elements present in the solid sample to be tested;

[0045] (12) Determine the major elements in the solid sample to be tested: Determine the major elements in the solid sample to be tested based on actual needs and the detection limit of LIBS technical analysis (when using the standard addition method, the mass fraction of the major element must be more than 20 times the detection limit of LIBS technology).

[0046] (13) selecting solid samples as samples, taking characteristic spectral lines of all major elements in the solid samples as sample features, and taking mass fractions of corresponding major elements in the solid samples as sample labels;

[0047] Select multiple solid samples with different mass fractions of major elements. According to the determined major elements, select multiple solid samples from the sample library that have the same shape as the solid sample to be tested and have different mass fractions of major elements (the span to be selected here should be larger, in order to make the mass fraction of the major element in the solid sample to be tested fall within the mass fraction range of the selected standard solid sample). LIBS spectra are collected for these standard solid samples. In view of the heterogeneity of solid samples, different positions need to be randomly selected for collection when collecting the spectrum of each standard solid sample, and abnormal spectra are eliminated. Subsequently, the remaining spectra are averaged to obtain the LIBS spectrum of each standard solid sample, ensuring that each standard solid sample corresponds to a spectrum; according to the LIBS spectrum obtained for each solid sample, the characteristic spectral lines of each major element are found from the NIST spectral line library, and the selected spectral lines of each solid sample are preprocessed. Similarly, the LIBS spectrum of the sample to be tested and the characteristic spectral lines of the major elements extracted from the LIBS spectrum can be obtained;

[0048] (14) constructing a main spectrum classification model based on the sample, inputting the characteristic spectrum lines of each main element in the solid sample to be tested into the spectrum classification model, and the spectrum classification model outputs the predicted value of the mass fraction of each main element in the solid sample to be tested;

[0049] Here, the partial least squares (PLS) method is used as an example to illustrate. For the results of the above data preprocessing, these data are randomly divided into training sets and prediction sets according to 2:1 or other ratios. Among them, the training set is used to establish the model, and the test set is used to evaluate the performance of the model. Finally, the actual mass fraction of the main elements in the solid sample to be tested and the PLS quantitative analysis model of the characteristic spectrum are obtained. The root mean square error (RMSE), determination coefficient (R 2 ) and other indicators to evaluate the established model. If the model evaluation indicators are not ideal, you can consider adjusting the model parameters or re-preprocessing the data. Predict the mass fraction of the main elements in the solid sample to be tested. Input the preprocessed solid sample data to the established PLS model to obtain the predicted value of the mass fraction of the main elements in the solid sample to be tested.

[0050] (15) Select two standard solid samples that have the same major element as the solid sample to be tested and have a similar mass fraction of the major element from the solid samples that meet the requirements of the standard addition method.

[0051] (2) The laser induced breakdown spectroscopy device collects LIBS spectral data of two solid sample groups under the same experimental factors, and the mass fraction of the first standard solid sample is different from the mass fraction of the second standard solid sample;

[0052] The solid sample to be tested is a sample with an unknown mass fraction of the element to be tested, and the standard solid sample is a sample with a known mass fraction of the element to be tested. The mass fractions of the element to be tested in the first standard solid sample and the second standard solid sample are known, but the mass fractions of the element to be tested are different. LIBS spectral data of the two solid sample groups are collected under the same experimental factors.

[0053] (3) The spectral intensity extracted from the LIBS spectra (laser induced breakdown spectroscopy) of the two solid sample groups is used to calculate the element mass fraction of the sample to be tested.

[0054] The spectral signal intensity and the mass fraction of the sample to be tested can be obtained according to the Boltzmann formula. The formula for the mass fraction of the element X to be tested and its spectral intensity is:

[0055]

[0056] Among them, I n is the emission line intensity of the sample to be tested, F nis the experimental factor of laser-induced breakdown spectroscopy, C n is the mass fraction of the element to be measured in the solid sample, A ki is the transition probability, g k is the statistical weight of the k-th layer, E ki is the upper level energy of the emission line, k B is the Boltzmann constant and U(T) is the partition function.

[0057] When the experimental factors are the same, the spectral intensity of the LIBS spectrum is directly proportional to the mass fraction of the substance, and the proportional coefficient is set to k. Then the above formula (1) can be simplified to:

[0058] I n =kC n (2)

[0059] Select the mass fractions of the elements to be tested as C s1 , C s2 The first standard solid sample and the second standard solid sample are simultaneously collected using a laser induced breakdown spectroscopy device that implements the solid sample standard addition method. The mass fraction of the element to be measured in the solid sample to be measured is C x , then the formula for the spectral intensity and mass fraction obtained by the laser induced breakdown spectroscopy device that implements the solid sample standard addition method is:

[0060] I1=k(C s1 +C x ) (3)

[0061] I2=k(C s2 +C x ) (4)

[0062] Among them, I1 and I2 are the spectral intensities in the LIBS spectral data of the two solid sample groups.

[0063] Combining formulas (3) and (4), we can get the mass fraction of the element to be measured in the solid sample: x for:

[0064]

[0065] In an embodiment of the present invention, a laser induced breakdown spectroscopy device for implementing a solid sample standard addition method simultaneously collects LIBS spectral data of a solid sample to be tested and a first standard solid sample, and of a solid sample to be tested and a second standard solid sample, and keeps the experimental factors of the two groups of solid samples substantially the same, that is, controls the energy density (including energy size and spot size) of the laser pulses focused on the two groups of solid samples to be the same, and the laser pulses focused on the two solid samples in each group of solid samples reach the same energy density at the same time. The structure of the laser induced breakdown spectroscopy device for implementing the above function is as follows: Figure 2 As shown, the laser induced breakdown spectroscopy device is as follows:

[0066] A laser (1), a laser beam emitted by the laser (1) enters a beam splitter (2), and the beam splitter (2) splits the laser beam into a transmission laser beam and a reflection laser beam having different propagation directions;

[0067] The reflected laser beam is incident on the first reflecting mirror (31), and after being turned 90 degrees, the reflected laser beam is incident on the laser energy attenuator (4) along the emission direction of the laser, and after being attenuated by the laser energy attenuator (4), enters the laser energy detector (51), and after being energy detected by the first laser energy detector (51), the attenuated reflected laser beam is input into the first plano-convex lens (61), and then input into the surface of the solid sample to be tested or the standard solid sample through the first plano-convex lens (61), and the surface of the solid sample to be tested or the standard solid sample is ablated to generate plasma (7), and the light generated by the energy level transition of the generated plasma (7) is coupled to one end of the Y-type quartz optical fiber (10) by the first collection head (91);

[0068] The transmitted laser beam is incident on the second reflector (32) at an incident angle of 45° and then emitted perpendicularly to the emission direction of the laser. It is then incident on the third reflector (33) at an incident angle of 45° and then emitted into the second laser energy detector (52) along the emission direction of the laser. The energy of the attenuated transmitted laser beam is detected by the second laser energy detector (52) and then input into the second plano-convex lens (62). The energy is then input into the surface of the solid sample to be tested or the standard solid sample through the second plano-convex lens (62). The surface of the solid sample to be tested or the standard solid sample is ablated to generate plasma (7). The light generated by the energy level transition of the generated plasma (7) is coupled to the other end of the Y-type quartz optical fiber (10) by the second collection head (92).

[0069] Light in the Y-shaped quartz optical fiber (10) is transmitted through a spectral slit (13) to a spectral detection device (14), and the spectral detection device (14) outputs a LIBS spectrum of light generated by energy level transition of the detected plasma through a computer (15); a laser and the spectral detection device (14) are connected through a BNC line (16), and after the laser emits laser light, a signal of the laser beam emitted by the laser is synchronously transmitted to the spectral detection device (14) through a BNC line 17, and the spectral detection device (14) collects LIBS spectrum data of light generated by energy level transition of the plasma after a set time delay.

[0070] Before collecting the spectrum of a solid sample group, the laser induced breakdown spectroscopy device needs to be debugged, including: (a) debugging the laser energy attenuator (4) so ​​that the energy of the attenuated reflected laser beam detected by the first laser energy detector (51) is the same as the energy of the transmitted laser beam detected by the second laser energy detector (52), ensuring that the laser energy of the transmitted laser beam and the reflected laser beam are the same before reaching the plano-convex lens; (b) the distance between the first plano-convex lens (61) and the second plano-convex lens (62) and the surface of the solid sample needs to be adjusted to the focal length of the plano-convex lens; (c) controlling the optical path of the transmitted laser beam and the reflected laser beam to reach the surface of the solid sample to be the same, so as to ensure that the size of the light spot focused on the surface of the solid sample is the same.

[0071] The laser beam emitted by the laser (1) is split by a beam splitter (2) into two transmission laser beams and a reflection laser beam with different propagation directions. The transmission laser beam and the reflection laser beam are simultaneously focused on two solid samples of the solid sample group with the same energy density through a subsequent optical path, respectively ablating the surfaces of the standard solid sample and the solid sample to be tested. The plasma generated by the ablation and the light generated by the energy level transition of the plasma are coupled to a Y-shaped quartz optical fiber by a collection head and then transmitted to a spectrum detection device (14). The spectrum detection device (14) collects LIBS spectrum data of the light generated by the energy level transition of the plasma. The beam splitter (2) needs to be selected according to the wavelength of the emitted laser beam, the splitting ratio of 1:1 and the polarization state of the emitted laser beam, so as to ensure that the laser beam emitted by the laser (1) is split into a transmission laser beam and a reflection laser beam with different propagation directions after passing through the beam splitter (2). The beam splitter has a splitting ratio of 1:1 and converts only the energy of the transmitted light and the reflected light into half of the energy of the laser output light after the splitting.

[0072] The reflected laser beam is incident on the first reflector (31) at an incident angle of 45°. After being turned 90°, the laser beam is emitted along the emission direction of the laser (1). After the reflected laser beam passes through the laser energy attenuator (4) to attenuate the energy of the beam, it enters the first laser energy detector (51) to monitor the energy of the beam after passing through the laser energy attenuator (4). The laser energy attenuator (4) is adjusted so that the energy of the attenuated reflected laser beam monitored by the first laser energy detector (51) is the same as the energy of the transmitted laser beam monitored by the second laser energy detector (52) in the transmission light path. Subsequently, the reflected laser beam passes through the first plano-convex lens (61). The beam focused by the first plano-convex lens (61) ablates the surface of the solid sample (8, 11) to generate plasma (7). The light generated by the energy level transition of the generated plasma (7) is coupled to one end of the Y-type quartz optical fiber (10) by the collection head (91). The solid sample (8) to be measured and the standard solid sample (11) are fixed on the station of the displacement platform (12).

[0073] The first reflector (31) is arranged to make the laser beam of the reflected light path turn to be emitted along the laser emission direction, so as to ensure that the reflected laser beam and the transmitted laser beam are focused by the plano-convex lens and irradiate the solid sample surfaces at two different positions of the displacement platform. The first plano-convex lens (61) and the second plano-convex lens (62) are moved forward and backward along the propagation direction of the laser beam through their respective manual linear displacement platforms (or manual linear slides) to adjust the distance between the plano-convex lens and the solid sample surface. The solid sample to be measured (8) and the standard solid sample (11) are fixed on the positions of the displacement platform (12). Use a laser rangefinder to first adjust the distance between the plano-convex lens and the surface of the solid sample to the focal length of the plano-convex lens, and record the knob reading of the manual linear translation stage at this time. The focal length of the focusing lens must also be within the measurement range of the laser rangefinder. If the measurement range of the laser rangefinder is 10cm-25cm and the accuracy is 10μm, the focal length of the lens is preferably within 150mm-200mm to facilitate subsequent adjustment of the distance between the plano-convex lens and the surface of the solid sample. The first plano-convex lens (61) and the second plano-convex lens (62) are vertically arranged to reduce experimental errors.

[0074] The transmitted laser beam after passing through the beam splitter 2 is incident on the second reflector (32) at an incident angle of 45° to generate a laser beam perpendicular to the emission direction of the laser (1), and then is incident on the third reflector (33) at an incident angle of 45° to generate a laser beam in the emission direction of the laser (1). The two reflectors (32, 33) are used to adjust the direction of the transmitted laser beam to ensure that the transmission light path of the transmitted laser beam to the surface of the solid sample and the reflection light path of the reflected laser beam to the surface of the solid sample are the same. The laser beam emitted by the third reflector (33) is monitored by the second laser energy detector (52) to ensure that the energy of the transmitted laser beam The laser energies of the transmitted laser beam and the reflected laser beam are the same before reaching the plano-convex lens. The transmitted light beam then propagates to the second plano-convex lens (62), where it is focused by the second plano-convex lens (62). The distance between the second plano-convex lens (62) and the surface of the standard solid sample (11) is the same as the distance between the first plano-convex lens (61) and the surface of the solid sample (8) to be measured. The transmitted light beam focused by the second plano-convex lens (62) ablates the surface of the solid standard sample (11) to generate plasma 7. The light generated by the generated plasma after energy level transition is coupled to the other end of the Y-type quartz optical fiber (10) by the second collector (92).

[0075] The displacement platform (12) is a three-dimensional electric displacement platform. By controlling the slow movement of the displacement platform, the possibility of repeated ablation of the standard solid sample and the solid sample to be tested by the laser is reduced, which is conducive to ensuring the stability of the LIBS spectrum; the solid sample to be tested (8) and the standard solid sample (11) placed on the same displacement platform (12) move simultaneously, in the same direction, and at the same speed. The Y-type quartz optical fiber (10) can pass the light band of 200nm-1200nm, and the spectral efficiency of the optical fiber at both ends is consistent. The first collection head (91) and the second collection head (92) are composed of two completely identical lens groups and the collection positions are set to be consistent, ensuring that the plasma collection efficiency of the standard solid sample and the solid sample to be tested is consistent.

[0076] A standard solid sample and a solid sample to be tested are placed at different positions, and the standard solid sample and the solid sample to be tested are ensured to move simultaneously, in the same direction, and at the same speed. The first reflector (31), the second reflector (32), and the third reflector (33) are required to have a reflectivity of 99.9% for the laser wavelength emitted by the laser; the laser energy attenuator (4) is a continuous circular gradient adjustable attenuator, which is used to adjust the energy of the reflected light path before the first plano-convex lens (61) to be the same as the energy of the transmitted light path before the second plano-convex lens (62). The laser energy detector is an optical power energy meter, which is used to intuitively reflect the energy of the reflected light path and the transmitted light path before the plano-convex lens.

[0077] The present invention has been described exemplarily. Obviously, the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for testing solid samples based on laser induced breakdown spectroscopy, characterized in that: The method is specifically as follows: (1) The solid sample to be tested and the first standard solid sample form a solid sample group, and the solid sample to be tested and the second standard solid sample form a solid sample group; (2) The laser-induced breakdown spectroscopy device collected LIBS spectral data of two solid sample groups under the same experimental factors; (3) The spectral intensities extracted from the LIBS spectra of the two solid sample groups are then used to calculate the elemental mass fractions of the samples to be tested; The mass fraction of the element to be measured in the first standard solid sample is different from the mass fraction of the element to be measured in the second standard solid sample.

2. The solid sample testing method based on laser induced breakdown spectroscopy as claimed in claim 1, characterized in that: Mass fraction of the element to be tested in the sample to be tested C x The calculation formula is as follows: Wherein, I1 and I2 are the spectral intensities in the LIBS spectral data of the solid sample group where the first standard solid sample is located and the solid sample group where the second standard solid sample is located, respectively; C s1 , C s2 are the mass fractions of the elements to be measured in the first standard solid sample and the second standard solid sample respectively.

3. The solid sample testing method based on laser induced breakdown spectroscopy as claimed in claim 1, characterized in that: The determination method of the standard solid sample is as follows: (11) collecting a LIBS spectrum of the solid sample to be tested, and determining the elements present in the solid sample to be tested based on the LIBS spectrum; (12) determining the major element in the solid sample to be tested, and extracting the characteristic spectral line of the major element from the LIBS spectrum of the solid sample to be tested; (13) screening solid samples as samples, taking characteristic spectral lines of all major elements in the solid samples as sample features, and using the mass fractions of the corresponding major elements in the solid samples as sample labels; (14) constructing a spectral classification model based on the sample, inputting the characteristic spectral lines of each major element in the solid sample to be tested into the spectral classification model, and the spectral classification model outputs a predicted value of the mass fraction of each major element in the solid sample to be tested; (15) Select two standard solid samples that have the same major element as the solid sample to be tested and have a similar mass fraction of the major element from the solid samples that meet the requirements of the standard addition method.

4. The solid sample testing method based on laser induced breakdown spectroscopy as claimed in claim 1, characterized in that: When the energy density of the laser pulses focused on the two groups of solid samples is the same, and the laser pulses focused on the two solid samples in each group of solid samples arrive at the same time, it is determined that the experimental factors of the two solid sample groups are the same.

5. The solid sample testing method based on laser induced breakdown spectroscopy as claimed in claim 1, characterized in that: The laser induced breakdown spectroscopy device includes: Laser, the laser beam emitted by the laser enters the beam splitter, and the beam splitter splits the laser beam into a transmitted laser beam and a reflected laser beam with inconsistent propagation directions; The reflected laser beam is incident on the first reflecting mirror, and after being turned 90 degrees, the reflected laser beam is incident on the laser energy attenuator along the emission direction of the laser. After being attenuated by the laser energy attenuator, the reflected laser beam enters the laser energy detector. The energy of the attenuated reflected laser beam is detected by the first laser energy detector and then input into the first plano-convex lens. The first plano-convex lens focuses on the surface of the solid sample to be tested or the standard solid sample, and ablates the surface of the solid sample to be tested or the standard solid sample to generate plasma. The light generated by the energy level transition of the generated plasma will be coupled to one end of the Y-type quartz optical fiber by the first collection head; The transmitted laser beam is incident on the second reflector at an incident angle of 45° and then emitted perpendicularly to the laser emission direction. It is then incident on the third reflector at an incident angle of 45° and then emitted into the second laser energy detector along the laser emission direction. The energy of the attenuated transmitted laser beam is detected by the second laser energy detector and then input into the second plano-convex lens. It is then input into the surface of the solid sample to be tested or the standard solid sample through the second plano-convex lens, and the surface of the solid sample to be tested or the standard solid sample is ablated to generate plasma. The light generated by the energy level transition of the generated plasma is coupled to the other end of the Y-type quartz optical fiber by the second collection head. The light in the Y-shaped quartz optical fiber is transmitted through the spectral slit to the spectral detection device, and the spectral detection device detects the LIBS spectrum of light generated by the energy level transition of the plasma; the laser and the spectral detection device are connected through a BNC line. After the laser emits the laser, the signal of the laser beam emitted by the laser is synchronously transmitted to the spectral detection device through the BNC line. The spectral detection device collects the LIBS spectrum data of the light generated by the energy level transition of the plasma after a set time delay.

6. The solid sample testing method based on laser induced breakdown spectroscopy as claimed in claim 5, characterized in that: The laser energy attenuator is adjusted so that the energy of the attenuated reflected laser beam detected by the first laser energy detector is the same as the energy of the transmitted laser beam detected by the second laser energy detector.

7. The solid sample testing method based on laser induced breakdown spectroscopy as claimed in claim 5, characterized in that: The distance between the first plano-convex lens and the second plano-convex lens and the surface of the solid sample is adjusted to the focal length of the plano-convex lens.

8. The solid sample testing method based on laser induced breakdown spectroscopy as claimed in claim 5, characterized in that: The optical paths of the transmitted laser beam and the reflected laser beam reaching the surface of the solid sample are controlled to be the same.

9. The solid sample testing method based on laser induced breakdown spectroscopy as claimed in claim 5, characterized in that: The first plano-convex lens and the second plano-convex lens can be moved forward and backward along the propagation direction of the laser beam to adjust the distance between the plano-convex lens and the surface of the solid sample.

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