LIBS (laser-induced breakdown spectroscopy) all-optical rapid detection device

Abstract

The invention discloses an LIBS (laser-induced breakdown spectroscopy) all-optical rapid detection device, and relates to the technical field of detection devices, the LIBS all-optical rapid detection device comprises a stand column, a detection head is mounted on the top surface of the stand column, a mounting box is arranged at the top of the detection head, and a laser emission module and a signal receiving module are arranged in the mounting box; the laser transmitting module comprises a pulse laser arranged in the mounting box through a support, a focusing lens arranged at a transmitting port of the pulse laser and a second prism arranged in the mounting box, a circular hole matched with the detection head is formed in the bottom surface of the mounting box, and a first prism is arranged above the circular hole; by using the laser emission module, a laser beam with high power density can be conveniently emitted, so that a small amount of material on the surface of a sample is instantaneously subjected to the processes of ablation, dissociation, atomization, ionization and the like to form plasma; and then collecting the optical radiation by using a signal receiving module, analyzing the optical radiation by using a spectrograph, and determining the chemical components and content of the sample according to spectral characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of detection devices, and in particular to a LIBS all-optical rapid detection device. Background Art

[0002] In many fields such as material analysis, environmental monitoring, and cultural relics identification, accurate detection of the chemical composition and content of samples is crucial; although traditional chemical analysis methods, such as wet chemical analysis, have certain advantages in accuracy, they have many limitations. It requires a complex sample pretreatment process, including sample dissolution, separation, enrichment and other steps. It is not only cumbersome and time-consuming, but also easy to introduce impurities, affecting the accuracy of the test results. Moreover, this method often consumes a large amount of chemical reagents, causing great pollution to the environment.

[0003] Although some existing detection technologies have overcome some shortcomings of traditional chemical analysis methods to a certain extent, they still have shortcomings; for example, some detection methods can only detect a single element or a few elements, and cannot comprehensively analyze multiple elements in a sample at one time, resulting in low detection efficiency. Some detection equipment is also bulky, expensive, and has strict requirements on the use environment, which limits its wide application in actual scenarios.

[0004] With the rapid development of modern industry and scientific research, higher requirements are placed on sample detection technology, requiring a new detection technology that can detect quickly, accurately, and contactlessly, and can analyze multiple elements simultaneously, and is suitable for various sample types and detection environments. Against this background, the LIBS all-optical rapid detection device of the present invention came into being, aiming to solve the shortcomings of existing detection technology and meet the needs of actual production and scientific research; The laser energy emitted by a pulsed laser is unstable. Unstable laser energy leads to inconsistent decomposition degree of samples during detection. When the energy is too high, the sample will be over-decomposed, generating complex and difficult-to-analyze spectral signals, which seriously interferes with the judgment of the true composition of the sample. When the energy is too low, the sample cannot effectively generate plasma, resulting in weak spectral signals or even undetectable, which greatly reduces the sensitivity and reliability of the detection, affects the accuracy of the test results, and makes the test results of different times vary greatly. Summary of the invention

[0005] In order to solve the problems in the background technology, the present invention proposes a LIBS all-optical rapid detection device.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A LIBS all-optical rapid detection device comprises a column, a detection head is installed on the top surface of the column, a mounting box is provided on the top of the detection head, and a laser emission module and a signal receiving module are arranged in the mounting box; The laser emission module includes a pulse laser arranged in an installation box through a bracket, a focusing lens arranged at the emission port of the pulse laser, and a second prism arranged in the installation box. A circular hole matching with the detection head is opened on the bottom surface of the installation box, and a prism is arranged above the circular hole. The signal receiving module includes a reflector and a coupling lens arranged in an installation box, a fiber optic spectrometer lead-out head is installed on the side of the installation box, and the fiber optic spectrometer lead-out head is coplanar with the coupling lens, and a spectrometer is arranged on one side of the fiber optic spectrometer lead-out head; An intelligent control module is also provided in the installation box, and the intelligent control module includes an analysis unit; The analysis unit analyzes the detected energy value data, determines the stability of the energy value after eliminating abnormal values, analyzes the optimal collection time point for the energy value data determined to be stable, analyzes the law of the optimal collection time point after obtaining the optimal collection time point, generates a detection signal according to the law, and transmits the detection signal to the execution unit.

[0007] Preferably, a camera is installed in the installation box via a track, a pull rod is provided on one side of the camera, and one end of the pull rod movably passes through the outside of the installation box, and the lens of the camera is coplanar with the reflector.

[0008] Preferably, a power supply is installed on the side of the installation box, and the power supply is electrically connected to the pulse laser and the camera through wires.

[0009] Preferably, the pulse laser, focusing lens, prism 2 and prism 1 are all coplanar.

[0010] Preferably, the intelligent control module further includes a collection unit and an execution unit; A collection unit monitors the energy value of the laser energy beam emitted by the pulse laser and transmits the detected data to the analysis unit; The execution unit receives the detection signal transmitted by the analysis unit, and then performs the detection operation according to the optimal collection time point.

[0011] Preferably, the analysis unit determines the stability of the energy value as follows: S1: Sort the energy value data detected within the set time period according to the collection time, and calculate the mean A and standard deviation B of the energy value data detected within the set time period, and use the calculated mean A and standard deviation B to establish the fluctuation range of the detected energy value data in the time period , marking the energy value data detected within the set time period that are not within the fluctuation range as abnormal values; S2: The number of outliers And the number of energy value data detected Perform statistics, if the comparison threshold is preset , it is determined that the energy value data detected in this time period fluctuates greatly and is inaccurate, and the time period is marked as a fluctuation time period; if the preset comparison threshold , it is determined that the energy value data detected within this time period is stable, the abnormal values ​​summarized in the detected energy value data are eliminated, and then the average value of the remaining energy value data is calculated.

[0012] Preferably, the analysis unit determines the optimal collection time point as follows: K1: According to the number of abnormal values ​​in the corresponding time period, the detection energy value data with the least number of abnormal values ​​are screened out and recorded as the stable detection group, and the non-abnormal value data in the stable detection group are compared with the preset normal range of energy data. If the non-abnormal value data in the stable detection group are all within the preset normal range of energy data, the laser energy is determined to be stable and the time period is marked as a stable time period; otherwise, the laser energy is determined to be unstable and the time period is marked as an unstable time period; K2: Sort the detection energy value data of the stable detection group in the order of acquisition time, draw and connect the coordinate points in the binary coordinate system constructed by the acquisition time and energy value data, calculate the slope of the connecting line, and take the absolute value of the slope; number the slopes of the corresponding connecting lines in the order of acquisition time, mark the absolute value of the slope at the corresponding acquisition time whose absolute value of the slope is less than the preset fluctuation threshold as a stable slope, and record the number of the stable slope; K3: Compare all stable slopes, select the minimum slope, and start from the number b of the minimum slope to the number and Diffusion is performed at the position, and the absolute values ​​of the slopes of the lines corresponding to the adjacent acquisition times are compared, and then the difference between the absolute values ​​of the slopes of the two is calculated, and the group with the smallest difference is selected, and the acquisition time corresponding to number b is taken as the stable time point; K4: If there are two or more groups with the smallest absolute slope difference, then the group numbered and Diffusion is performed again at the position, and the group with the smallest difference is screened again. If there are still two or more groups with the smallest difference in absolute values ​​of slopes, diffusion is performed to both sides again until one group of data remains. The collection time corresponding to the starting point number of this group of data is recorded as the optimal collection time point.

[0013] Preferably, the analysis unit performs the following steps to analyze the law of the optimal collection time point: M1: retrieve the historical data, mark the best acquisition time point in the historical data, calculate the time difference between adjacent best acquisition time points and compare them, calculate the mean of the calculated time difference data, and if the time difference data is equal to the time difference mean, If the difference between them is less than or equal to the preset difference threshold, it is determined that there is a regularity in the optimal collection time point, and the interval time is equal to the mean time difference. , after the last best acquisition time point, the time After that, a detection signal is generated and transmitted to the execution unit, and the execution unit performs a sample detection operation; M2: If the time difference data and the time difference mean If the difference between the two time difference data is greater than the preset difference threshold, it is determined that there is no regularity in the best acquisition time point. The calculated time difference data are arranged in order of size, and a comparative difference threshold is preset. If the difference between the two time difference data is less than the preset comparative difference threshold, the two time difference data are recorded as the same fluctuation time difference. The number of time difference data with the same fluctuation time difference is counted, and the mean of the time difference data with the largest number is taken as the average value. As the regular fluctuation time, after the last best collection time point, the time After that, a detection signal is generated and transmitted to the execution unit, which performs sample detection operation.

[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. Through the use of laser emission module, it is convenient to emit high-power density laser beam, and use high-power density laser beam to focus on the sample surface, so that a small amount of material on the sample surface will instantly undergo ablation, dissociation, atomization and ionization processes to form plasma, and when the atoms and ions in the excited state transition to the low energy level or ground state, they will emit light radiation of a specific wavelength; then the signal receiving module is used to collect these light radiations, and the spectrometer is used to analyze them, and the chemical composition and content of the sample are determined according to the spectral characteristics; at the same time, when testing the sample, there is no need to directly contact the sample, avoiding contamination and damage to the sample, and no complicated sample preparation process is required; at the same time, multiple elements can be detected at the same time, whether it is the main element or trace element in the sample, the analysis result can be obtained in one measurement, and the analysis can be performed at the original position of the sample, without taking the sample out of its environment, which is suitable for analyzing large samples or samples that are difficult to move; 2. The analysis unit analyzes and eliminates abnormal values ​​in the detected energy value data, and then determines the stability of the energy value data by comparing the ratio of the number of abnormal values ​​to the number of detected energy value data and the preset comparison threshold, so as to avoid the adverse effects of energy instability on the detection results; the analysis unit analyzes the stable energy value data, determines the optimal collection time point, improves the quality and accuracy of the detection data, and reduces the detection errors caused by inappropriate collection time; the analysis unit retrieves the detection history data for analysis, determines the law of the optimal collection time point, and generates a detection signal for sample detection operation according to the law after a certain period of time after the last optimal collection time point. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It shows a schematic structural diagram of a front viewing angle provided by an embodiment of the present invention; Figure 2 A schematic diagram of a cross-sectional structure from a top view provided by an embodiment of the present invention is shown; Figure 3 A schematic diagram of a cross-sectional structure from a side perspective provided by an embodiment of the present invention is shown; Figure 4 It shows a schematic diagram of the structure of the installation box according to the top view provided by an embodiment of the present invention; Figure 5 A system flow chart provided according to an embodiment of the present invention is shown.

[0016] Legend: 1. Column; 2. Detection head; 3. Power supply; 4. Installation box; 5. Fiber optic spectrometer lead; 6. Prism 1; 7. Focusing lens; 8. Pulse laser; 9. Coupling lens; 10. Camera; 11. Bracket; 12. Circular hole; 13. Prism 2; 14. Reflector. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1 - Figure 5 , the present invention provides a technical solution: A LIBS all-optical rapid detection device comprises a column 1, and a plurality of threaded holes are provided on the bottom surface of the column 1, so that the column 1 can be fixedly mounted on a sample platform (not shown in the figure, for placing samples) by bolts; a detection head 2 is mounted on the top surface of the column 1 for detecting samples; a mounting box 4 is provided on the top of the detection head 2, and a laser emission module and a signal receiving module are arranged in the mounting box 4; by using the laser emission module, a high-power-density laser beam is easily emitted, and the high-power-density laser beam is focused on the sample surface, so that a small amount of material on the sample surface undergoes ablation, dissociation, atomization and ionization processes in an instant, forming plasma, and atoms and ions in an excited state move toward a low-power state. When the energy level or ground state transitions, light radiation of a specific wavelength will be emitted; then the light radiation is collected by the signal receiving module and analyzed by the spectrometer to determine the chemical composition and content of the sample based on the spectral characteristics; at the same time, when testing the sample, there is no need to directly contact the sample, avoiding contamination and damage to the sample, and no need for complicated sample preparation process; at the same time, multiple elements can be detected at the same time, whether it is the main element or trace element in the sample, the analysis result can be obtained in one measurement, and the sample can be analyzed at its original position without taking the sample out of its environment, which is suitable for analyzing large samples or samples that are difficult to move; The laser emission module includes a pulse laser 8 arranged in the installation box 4 through a bracket 11, which is used to emit a laser beam, so as to facilitate the decomposition of the sample; a focusing lens 7 is arranged at the emission port of the pulse laser 8, and through the use of the focusing lens 7, the laser beam of the pulse laser 8 is focused on a smaller area on the surface of the sample, so that the energy of the laser beam is concentrated in a small range, thereby increasing the energy density of the laser beam on the surface of the sample, so that enough energy can be generated on the surface of the sample, so that the sample is instantly evaporated and ionized to form plasma; a prism 13 is arranged in the installation box 4, which is used to change the direction of movement of the laser beam, so as to facilitate the laser beam to be irradiated onto the sample; a circular hole 12 is opened on the bottom surface of the installation box 4 to match the detection head 2, so that the laser beam can flow into the detection head 2, so as to achieve the decomposition of the sample; a prism 1 6 is arranged above the circular hole 12, which is used to change the direction of movement of the laser beam, so as to facilitate the laser beam to be irradiated onto the sample; The signal receiving module includes a reflector 14 and a coupling lens 9 arranged in the installation box 4. The use of the reflector 14 is convenient for changing the direction of signal transmission, thereby facilitating the spectrometer to receive the signal; the use of the coupling lens 9 collects the plasma light signals emitted from various directions on the sample surface and converges them to a specific direction, so that they can enter the incident slit of the optical fiber or the spectrometer, which is beneficial for the subsequent analysis and detection of the spectrum; an optical fiber spectrometer lead-out head 5 is installed on the side of the installation box 4 to facilitate the transmission of the signal to the spectrometer; and the optical fiber spectrometer lead-out head 5 is coplanar with the coupling lens 9, and a spectrometer (not shown in the figure, used to detect the composition of the sample) is provided on one side of the optical fiber spectrometer lead-out head 5.

[0019] In the present invention, a camera 10 is installed in the installation box 4 through a track, a pull rod is provided on one side of the camera 10, and one end of the pull rod is movably extended out of the installation box 4, and the lens of the camera 10 is coplanar with the reflector 14. Through the use of the camera 10, it is convenient to collect the plasma generated by the sample, and multiple collections are required to obtain sufficient spectral data for analysis. At the same time, the stability and repeatability of the signal can also be evaluated through multiple collections.

[0020] In the present invention, a power supply 3 is installed on the side of the installation box 4, and the power supply 3 is electrically connected to the pulse laser 8 and the camera 10 through wires, so as to provide power to the pulse laser 8 and the camera 10.

[0021] In the present invention, the pulse laser 8, the focusing lens 7, the prism 2 13 and the prism 1 6 are all coplanar, which facilitates the refraction of the laser beam, thereby facilitating the refraction of the laser beam onto the sample, thereby facilitating the decomposition of the sample.

[0022] An intelligent control module is also provided in the installation box, and the intelligent control module includes a collection unit, an analysis unit and an execution unit; The energy value of the emitted laser beam is detected by the energy monitoring sensor installed on the pulse laser 8, and the energy value data detected in the set time period are sorted according to the acquisition time, and the mean value A and standard deviation B of the energy value data detected in the set time period are calculated, and the fluctuation range of the detected energy value data in the time period is established by the calculated mean value A and standard deviation B , the energy value data detected within the set time period that is not within the fluctuation range is marked as an outlier, and the number of outliers is And the number of energy value data detected Perform statistics, if the comparison threshold is preset , it is determined that the energy value data detected in this time period fluctuates greatly and is inaccurate, and the time period is marked as a fluctuation time period; if the preset comparison threshold , it is determined that the energy value data detected in this time period is stable, the abnormal values ​​of the detected energy value data are eliminated, and then the average value of the remaining energy value data is calculated; According to the number of abnormal values ​​in the corresponding time period, the detection energy value data with the least number of abnormal values ​​are screened out and recorded as a stable detection group, and the non-abnormal value data in the stable detection group are compared with the preset normal range of energy data. If the non-abnormal value data in the stable detection group are all within the preset normal range of energy data, it is determined that the laser energy is stable and the time period is marked as a stable time period; otherwise, it is determined that the laser energy is unstable and the time period is marked as an unstable time period; The detection energy value data of the stable detection group are sorted in the order of acquisition time, and the coordinate points are drawn and connected in the binary coordinate system constructed by the acquisition time and energy value data, the slope of the connecting line is calculated, and the absolute value of the slope is taken; the slopes of the corresponding connecting lines are numbered according to the order of acquisition time, and the absolute value of the slope at the corresponding acquisition time whose absolute value of the slope is less than the preset fluctuation threshold is marked as a stable slope, and the number of the stable slope is recorded; all stable slopes are compared, the minimum slope value is screened out, and the number of the stable slope is recorded, starting from the number b of the minimum slope value. and The diffusion is performed at the position, and the absolute values ​​of the slopes of the lines corresponding to the adjacent acquisition times are compared. Then, the difference between the absolute values ​​of the slopes of the two is calculated, and the group with the smallest difference is selected, and the acquisition time corresponding to number b is taken as the stable time point; if there are two or more groups with the smallest absolute value difference of the slopes, the group with the smallest absolute value difference of the slopes is selected. and Diffusion is performed again at the position, and the group with the smallest difference is screened again. If there are still two or more groups with the smallest slope absolute value difference, diffusion is performed again to both sides until one group of data remains. The collection time corresponding to the starting point number of this group of data is recorded as the optimal collection time point; Retrieve the historical data of the test, mark the best collection time point in the historical data, then calculate the time difference between adjacent best collection time points and compare them, calculate the mean of the calculated time difference data, and if the time difference data is equal to the time difference mean If the difference between them is less than or equal to the preset difference threshold, it is determined that there is a regularity in the optimal collection time point, and the interval time is equal to the mean time difference. , after the last best acquisition time point, the time After that, a detection signal is generated and transmitted to the execution unit, and the execution unit performs a sample detection operation; If the time difference data and the time difference mean If the difference between the two time difference data is greater than the preset difference threshold, it is determined that there is no regularity in the best acquisition time point. The calculated time difference data are arranged in order of size, and a comparative difference threshold is preset. If the difference between the two time difference data is less than the preset comparative difference threshold, the two time difference data are recorded as the same fluctuation time difference. The number of time difference data with the same fluctuation time difference is counted, and the mean of the time difference data with the largest number is taken as the average value. As the regular fluctuation time, after the last best collection time point, the time After that, a detection signal is generated and transmitted to the execution unit, which performs sample detection operation.

[0023] Working principle: When the present invention is used, the sample is first placed on the sample platform, and then the detection head 2 is adjusted to align the detection head 2 with the sample, and then the pulse laser 8 is turned on. The laser beam emitted by the pulse laser 8 passes through the focusing lens 7, and then refracts onto the prism 2 13, and then refracts onto the prism 1 6, and finally passes through the circular hole 12 to enter the detection head 2, and finally irradiates the sample through the detection head 2, so that the sample is decomposed into plasma; Then the detection head 2 decomposes the sample into a light radiation signal of plasma to the reflector 14, so that the light radiation signal is transmitted to the coupling lens 9, and then the light radiation signal enters the spectrometer through the optical fiber spectrometer output head 5, and the composition of the sample is analyzed by the spectrometer; Among them, through the use of camera 10, the plasma generated by the sample can be collected multiple times to obtain sufficient spectral data for analysis, and the stability and repeatability of the signal can also be evaluated through multiple collections.

[0024] The above description of the embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A LIBS all-optical rapid detection device, comprising a column (1), characterized in that: A detection head (2) is installed on the top surface of the column (1), a mounting box (4) is provided on the top of the detection head (2), and a laser emission module and a signal receiving module are provided in the mounting box (4); The laser emission module comprises a pulse laser (8) arranged in an installation box (4) via a bracket (11), a focusing lens (7) arranged at an emission port of the pulse laser (8), and a second prism (13) arranged in the installation box (4); a circular hole (12) matching with the detection head (2) is formed on the bottom surface of the installation box (4), and a first prism (6) is arranged above the circular hole (12); The signal receiving module comprises a reflector (14) and a coupling lens (9) arranged in a mounting box (4); a fiber optic spectrometer lead-out head (5) is mounted on a side of the mounting box (4); the fiber optic spectrometer lead-out head (5) is coplanar with the coupling lens (9); and a spectrometer is provided on one side of the fiber optic spectrometer lead-out head (5); An intelligent control module is also provided in the installation box, and the intelligent control module includes an analysis unit; The analysis unit analyzes the detected energy value data, determines the stability of the energy value after eliminating abnormal values, analyzes the optimal collection time point for the energy value data determined to be stable, analyzes the law of the optimal collection time point after obtaining the optimal collection time point, generates a detection signal according to the law, and transmits the detection signal to the execution unit.

2. A LIBS all-optical rapid detection device according to claim 1, characterized in that: A camera (10) is installed in the installation box (4) via a track, a pull rod is provided on one side of the camera (10), and one end of the pull rod movably passes through the outside of the installation box (4), and the lens of the camera (10) is coplanar with the reflector (14).

3. A LIBS all-optical rapid detection device according to claim 2, characterized in that: A power source (3) is installed on the side of the installation box (4), and the power source (3) is electrically connected to the pulse laser (8) and the camera (10) via wires.

4. A LIBS all-optical rapid detection device according to claim 3, characterized in that: The pulse laser (8), the focusing lens (7), the second prism (13) and the first prism (6) are all coplanar.

5. The LIBS all-optical rapid detection device according to claim 1, characterized in that: The intelligent control module also includes a collection unit and an execution unit; A collection unit monitors the energy value of the laser energy beam emitted by the pulse laser (8) and transmits the detected data to the analysis unit; The execution unit receives the detection signal transmitted by the analysis unit, and then performs the detection operation according to the optimal collection time point.

6. A LIBS all-optical rapid detection device according to claim 5, characterized in that: The analysis unit determines the stability of the energy value as follows: S1: Sort the energy value data detected within the set time period according to the collection time, and calculate the mean A and standard deviation B of the energy value data detected within the set time period, and use the calculated mean A and standard deviation B to establish the fluctuation range of the detected energy value data in this time period , marking the energy value data detected within the set time period that are not within the fluctuation range as abnormal values; S2: The number of outliers And the number of energy value data detected Perform statistics, if the comparison threshold is preset , it is determined that the energy value data detected in this time period fluctuates greatly and is inaccurate, and the time period is marked as a fluctuation time period; if the preset comparison threshold , it is determined that the energy value data detected within this time period is stable, the abnormal values ​​summarized in the detected energy value data are eliminated, and then the average value of the remaining energy value data is calculated.

7. A LIBS all-optical rapid detection device according to claim 6, characterized in that: The analysis unit determines the optimal collection time point as follows: K1: According to the number of abnormal values ​​in the corresponding time period, the detection energy value data with the least number of abnormal values ​​are screened out and recorded as the stable detection group, and the non-abnormal value data in the stable detection group are compared with the preset normal range of energy data. If the non-abnormal value data in the stable detection group are all within the preset normal range of energy data, the laser energy is determined to be stable and the time period is marked as a stable time period; otherwise, the laser energy is determined to be unstable and the time period is marked as an unstable time period; K2: Sort the detection energy value data of the stable detection group in the order of acquisition time, draw and connect the coordinate points in the binary coordinate system constructed by the acquisition time and energy value data, calculate the slope of the connecting line, and take the absolute value of the slope; number the slopes of the corresponding connecting lines in the order of acquisition time, mark the absolute value of the slope at the corresponding acquisition time whose absolute value of the slope is less than the preset fluctuation threshold as a stable slope, and record the number of the stable slope; K3: Compare all stable slopes, select the minimum slope, and start from the number b of the minimum slope to the number and Diffusion is performed at the position, and the absolute values ​​of the slopes of the lines corresponding to the adjacent acquisition times are compared, and then the difference between the absolute values ​​of the slopes of the two is calculated, and the group with the smallest difference is selected, and the acquisition time corresponding to number b is taken as the stable time point; K4: If there are two or more groups with the smallest absolute difference in slope, then the group numbered and Diffusion is performed again at the position, and the group with the smallest difference is screened again. If there are still two or more groups with the smallest difference in absolute values ​​of slopes, diffusion is performed to both sides again until one group of data remains. The collection time corresponding to the starting point number of this group of data is recorded as the optimal collection time point.

8. A LIBS all-optical rapid detection device according to claim 7, characterized in that: The analysis steps for the analysis unit to analyze the rules of the optimal collection time points are as follows: M1: retrieve the historical data, mark the best acquisition time point in the historical data, calculate the time difference between adjacent best acquisition time points and compare them, calculate the mean of the calculated time difference data, and if the time difference data is equal to the time difference mean, If the difference between them is less than or equal to the preset difference threshold, it is determined that there is a regularity in the optimal collection time point, and the interval time is equal to the mean time difference. , after the last best acquisition time point, the time After that, a detection signal is generated and transmitted to the execution unit, and the execution unit performs a sample detection operation; M2: If the time difference data and the time difference mean If the difference between the two time difference data is greater than the preset difference threshold, it is determined that there is no regularity in the best acquisition time point. The calculated time difference data are arranged in order of size, and a comparative difference threshold is preset. If the difference between the two time difference data is less than the preset comparative difference threshold, the two time difference data are recorded as the same fluctuation time difference. The number of time difference data with the same fluctuation time difference is counted, and the mean of the time difference data with the largest number is taken as the average value. As the regular fluctuation time, after the last best collection time point, the time After that, a detection signal is generated and transmitted to the execution unit, and the execution unit performs sample detection operation.

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