Plasma radiation region matching method and device based on collection field adjustment

Abstract

The application belongs to the technical field of laser-induced breakdown spectroscopy, and specifically discloses a plasma radiation region matching method and device based on collection field adjustment. According to the application, plasma is generated based on a laser-induced breakdown spectroscopy system; a multi-range collection field is determined based on a single lens or a zoom lens group with different focal lengths; a field evaluation index is calculated according to the emission spectrum of each plasma and a target analysis spectral line, and the optimal collection field is determined according to the field evaluation index, and the trace elements in the aluminum alloy sample are quantitatively analyzed under the optimal collection field. In the above manner, the optimal collection field meeting the field evaluation index is determined according to the spatial distribution characteristics of the plasma radiation by using the single lens or the zoom lens group with different focal lengths, the collection efficiency under different optical system configurations is the highest, and the trace elements in the aluminum alloy sample are quantitatively analyzed under the optimal collection field, so that the efficiency and accuracy of analyzing the trace elements can be effectively improved.

Description

Technical Field

[0001] This application belongs to the field of laser-induced breakdown spectroscopy technology, and more specifically, relates to a plasma radiation region matching method and apparatus based on acquisition field-of-view adjustment. Background Technology

[0002] Laser-induced breakdown spectroscopy (LIBS), as an atomic emission spectroscopy technique, has the characteristics of being in-situ, real-time, and non-contact, and is widely used in fields such as deep space exploration, deep sea exploration, mineral exploration, and hazardous materials identification.

[0003] Currently, LIBS improves the applicability of long-distance LIBS detection to some extent by changing the focal length of the optical system to adapt to different detection distances. However, this method adjusts the focal length according to changes in detection distance, and the acquisition field of view of the optical system is still determined by the imaging relationship. It cannot achieve a match between the acquisition field of view and the spatial distribution of plasma radiation, resulting in the acquisition field of view not meeting actual needs. Furthermore, it cannot continuously adjust the acquisition field of view when needs change. Therefore, the efficiency and accuracy of the above method in analyzing trace elements are relatively low. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this application is to provide a plasma radiation region matching method and apparatus based on acquisition field adjustment, aiming to solve the problems of low efficiency and accuracy in the analysis of trace elements caused by the inability of existing technologies to match the acquisition field with the spatial distribution of plasma radiation and the inability to achieve continuous adjustment of the acquisition field.

[0005] To achieve the above objectives, in a first aspect, this application provides a plasma radiation region matching method based on acquisition field-of-view adjustment, comprising: Based on a laser-induced breakdown spectroscopy system, a high-energy laser is focused onto the surface of an aluminum alloy sample at a distance to generate plasma; A multi-range acquisition field of view is determined based on single lenses or zoom lens groups with different focal lengths, the radiation light emitted by the plasma is converged, and the converged plasma radiation light is coupled to a multimode fiber. Under the multi-range acquisition field of view, multiple laser pulses are applied to different positions on the surface of the aluminum alloy sample, and the plasma emission spectrum corresponding to each laser pulse is acquired by a single-channel spectrometer. The field-of-view evaluation index of the multi-range acquisition field of view is calculated based on the plasma emission spectrum and target analysis spectral lines, and the optimal acquisition field of view is determined based on the field-of-view evaluation index. Under the optimal acquisition field of view, the trace elements in the aluminum alloy sample are quantitatively analyzed.

[0006] In one embodiment, before the steps of determining a multi-range acquisition field of view based on single lenses or zoom lens groups with different focal lengths, converging the radiation light emitted by the plasma, and coupling the converged plasma radiation light to a multimode fiber, the method further includes: When a change is detected in a single lens, the focal plane of the changed single lens is calibrated. Obtain the current focal length and fixed object distance of the calibrated single lens, and calculate the target image distance based on the current focal length and the fixed object distance; Calculate the lateral magnification based on the target image distance and the fixed object distance; A first acquisition field of view corresponding to the current focal length is determined based on the lateral magnification and the core diameter of the multimode fiber, and a multi-range acquisition field of view is determined based on each of the first acquisition fields of view.

[0007] In one embodiment, the step of performing focal plane calibration on the changed single lens when a change is detected includes: When a change is detected in a single lens, the visible light calibration light source is controlled to couple into the multimode fiber from the output end. Based on the modified single lens, the light emitted from the incident end of the multimode fiber facing the single lens is controlled, and the emitted visible light calibration light source is focused on the surface of the aluminum alloy sample to obtain the calibration light spot on the surface of the aluminum alloy sample. The position of the optical fiber incident end is continuously adjusted along the optical axis until the area of ​​the calibration spot is minimized and the sharpness characteristic value is maximized, so as to achieve focal plane calibration of the changed single lens.

[0008] In one embodiment, before the steps of determining a multi-range acquisition field of view based on single lenses or zoom lens groups with different focal lengths, converging the radiation light emitted by the plasma, and coupling the converged plasma radiation light to a multimode fiber, the method further includes: When a change in the position of the concave lens in the zoom lens group is detected, the zoom lens group is calibrated to the focal plane. For each distance between the concave lens and the target convex lens, the corresponding image plane position is determined according to the principle of minimizing the root mean square radius of the image plane spot, and the imaging size of the plasma radiation region at the image plane position is obtained. The characteristic dimensions of the plasma radiation region are obtained, and a second acquisition field of view is determined based on the imaging size, the characteristic dimensions, and the core diameter of the multimode fiber. A multi-range acquisition field of view is determined based on the movement range of the spacing and each of the second acquisition fields of view.

[0009] In one embodiment, the step of calculating the field-of-view evaluation index of the multi-range acquisition field of view based on each of the plasma emission spectra and target analysis spectral lines, determining the optimal acquisition field of view based on the field-of-view evaluation index, and performing quantitative analysis of trace elements in the aluminum alloy sample under the optimal acquisition field of view includes: The field-of-view evaluation index of the multi-range acquisition field of view is calculated based on the plasma emission spectrum and target analysis spectral line, and the field-of-view generation index-field curve is calculated based on the field-of-view evaluation index and the multi-range acquisition field of view generation index. Analyze the trend of index change in the index-field-of-view curve; Based on the trend analysis results, the optimal field of view evaluation index that meets the requirements is determined, and the acquisition field of view corresponding to the optimal field of view evaluation index is taken as the optimal acquisition field of view. Quantitative analysis of trace elements in aluminum alloy samples was performed under the optimal acquisition field of view.

[0010] In one embodiment, the step of quantitatively analyzing trace elements in the aluminum alloy sample under the optimal acquisition field of view includes: The main part for acquiring the high-radiation region of plasma; Determine the coverage area of ​​the optimal field of view; When the coverage area exactly covers the main body, the field analysis indexes of the optimal acquisition field of view and other acquisition fields of view are calculated respectively. When the quantitative analysis stability of the optimal acquisition field of view is determined to be higher than that of the other acquisition fields of view based on the field of view analysis index, the trace elements in the aluminum alloy sample are quantitatively analyzed under the optimal acquisition field of view.

[0011] Secondly, this application provides a plasma radiation region matching device based on acquisition field-of-view adjustment, comprising: The generation module is used to focus a high-energy laser onto the surface of an aluminum alloy sample at a distance based on a laser-induced breakdown spectroscopy system to generate plasma. The determination module is used to determine a multi-range acquisition field of view based on single lenses or zoom lens groups with different focal lengths, converge the radiation light emitted by the plasma, and couple the converged plasma radiation light to a multimode fiber. The acquisition module is used to apply multiple laser pulses to different positions on the surface of the aluminum alloy sample under the multi-range acquisition field of view, and to acquire the plasma emission spectrum corresponding to each laser pulse through a single-channel spectrometer. The determining module is further configured to calculate the field-of-view evaluation index of the multi-range acquisition field of view based on each of the plasma emission spectra and target analysis spectral lines, and determine the optimal acquisition field of view based on the field-of-view evaluation index, and perform quantitative analysis of trace elements in the aluminum alloy sample under the optimal acquisition field of view.

[0012] Thirdly, this application provides an electronic device, comprising: at least one memory for storing a program; and at least one processor for executing the program stored in the memory, wherein when the program stored in the memory is executed, the processor is configured to execute the method described in the first aspect or any possible implementation thereof.

[0013] Fourthly, this application provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to perform the method described in the first aspect or any possible implementation thereof.

[0014] Fifthly, this application provides a computer program product that, when run on a processor, causes the processor to perform the method described in the first aspect or any possible implementation thereof.

[0015] It is understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0016] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: (1) After generating plasma based on the laser-induced breakdown spectroscopy system, this application introduces single lenses or zoom lens groups with different focal lengths to determine a multi-range acquisition field of view, realizes the graded adjustment of seven different acquisition fields of view or the continuous change of the acquisition field of view within a certain range, and after acquiring laser pulses at different positions on the surface of the aluminum alloy sample, under the multi-range acquisition field of view, multiple laser pulses are applied to different positions on the surface of the aluminum alloy sample, and the plasma emission spectrum corresponding to each laser pulse is acquired by a single-channel spectrometer. The optimal acquisition field of view is determined according to the field of view evaluation index. The optimal acquisition field of view corresponds to the optimal matching state between the high radiation region of the plasma and the acquisition area. Under the optimal acquisition field of view, the trace elements in the aluminum alloy sample are quantitatively analyzed, realizing high sensitivity, high signal-to-noise ratio, and high stability long-distance laser-induced breakdown spectroscopy detection, thereby effectively improving the efficiency and accuracy of trace element analysis.

[0017] (2) This application also compares the optimal acquisition field of view determined from the perspective of a single lens or a zoom lens. The final determination of the optimal acquisition field of view is determined by the spatial distribution characteristics of plasma radiation, which is independent of the specific optical system used, thus demonstrating the universality of the technical solution of this application. Regardless of whether it is a single lens or a zoom lens group with different focal lengths, before determining the multi-range acquisition field of view, focal plane calibration is performed when a change is detected in the single lens or a change in the position of the concave lens in the zoom lens group. This ensures that the fiber incident end face is precisely located at the focal plane under that focal length. The wavelength of the visible light calibration light source is close to the target analysis spectrum, which can effectively reduce the influence of chromatic aberration on the focusing position.

[0018] In summary, this application utilizes a laser-induced breakdown spectroscopy system to focus a high-energy laser onto the surface of a distant aluminum alloy sample to generate plasma. A multi-range acquisition field of view is determined based on single lenses or zoom lens groups with different focal lengths. The radiation emitted by the plasma is converged and coupled to a multimode fiber. Under these multi-range acquisition fields of view, multiple laser pulses are applied to different positions on the surface of the aluminum alloy sample, and the plasma emission spectra corresponding to each laser pulse are acquired using a single-channel spectrometer. Based on the plasma emission spectra and target analysis lines, a field-of-view evaluation index for the multi-range acquisition field of view is calculated. The optimal acquisition field of view is then determined based on this evaluation index, and quantitative analysis of trace elements in the aluminum alloy sample is performed under this optimal field of view. By employing single lenses or zoom lens groups with different focal lengths and determining the optimal acquisition field of view based on the spatial distribution characteristics of plasma radiation, the acquisition efficiency is highest under different optical system configurations. Furthermore, quantitative analysis of trace elements in the aluminum alloy sample is performed under the optimal acquisition field of view, thereby effectively improving the efficiency and accuracy of trace element analysis. Attached Figure Description

[0019] Figure 1 This is one of the flowcharts of the plasma radiation region matching method based on acquisition field of view adjustment provided in the embodiments of this application; Figure 2 This is a schematic diagram of the overall structure provided in the embodiments of this application; Figure 3 This is a schematic diagram of the plasma radiation distribution provided in an embodiment of this application; Figure 4 This is the second flowchart of the plasma radiation region matching method based on acquisition field of view adjustment provided in the embodiments of this application; Figure 5(a) is a schematic diagram of the spectral intensity index-field curves plotted based on single lenses with different focal lengths according to the embodiments of this application; Figure 5(b) is a schematic diagram of the signal-to-noise ratio and relative standard deviation index-field curves based on single lenses with different focal lengths provided in the embodiments of this application; Figure 6(a) is a schematic diagram of the spectral intensity index-field curve based on the zoom lens group provided in the embodiment of this application; Figure 6(b) is a schematic diagram of the signal-to-noise ratio and relative standard deviation index-field curves based on the zoom lens group provided in the embodiments of this application; Figure 7 This is a schematic diagram of the module structure of the plasma radiation region matching device based on acquisition field of view adjustment provided in the embodiments of this application; Figure 8 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] In this article, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The symbol " / " in this article indicates that the related objects are in an "or" relationship; for example, A / B means A or B.

[0022] The terms "first" and "second," etc., used in the specification and claims herein are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages.

[0023] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0024] Based on this, embodiments of this application provide a plasma radiation region matching method based on acquisition field-of-view adjustment, referring to... Figure 1 , Figure 1 This is one of the flowcharts illustrating the plasma radiation region matching method based on acquisition field-of-view adjustment provided in this application embodiment. In this embodiment, the plasma radiation region matching method based on acquisition field-of-view adjustment includes steps S10 to S40: Step S10: Based on the laser-induced breakdown spectroscopy system, a high-energy laser is focused onto the surface of an aluminum alloy sample at a distance to generate plasma.

[0025] refer to Figure 2 , Figure 2 The diagram shows the overall structure as follows: 1 represents a Q-switched Nd:YAG laser, 2 represents a reflector, 3 represents a plano-concave lens, 4 represents a plano-convex lens, used to form a laser beam expanding and focusing lens group, 5 represents the surface of the aluminum alloy sample at a distance, 6 represents plasma, 7 represents the first plano-convex lens, 8 represents the second plano-convex lens, 9 represents a plano-concave lens, 10 represents a multimode fiber, 11 represents a single-channel spectrometer, 12 represents a computer, and 13 represents an ICCD camera.

[0026] It should be understood that, for the laser-induced breakdown spectroscopy system, the excitation source is a Q-switched Nd:YAG laser with an output wavelength of 1064 nm and a pulse energy of approximately 90 mJ. The high-energy laser, after passing through a beam-expanding and focusing lens group consisting of a -100 mm plano-concave lens and a 150 mm plano-convex lens, is focused onto the surface of a distant aluminum alloy sample. Plasma is generated by ablating the aluminum alloy sample. Various particles in this plasma collide with each other, producing bremsstrahlung and recombination radiation. During the continuous expansion and cooling of the plasma, atoms and ions in the excited state transition to lower energy levels or the ground state, spontaneously emitting characteristic spectral lines corresponding to the corresponding energy levels.

[0027] Step S20: Determine a multi-range acquisition field of view based on single lenses or zoom lens groups with different focal lengths, converge the radiation light emitted by the plasma, and couple the converged plasma radiation light to a multimode fiber.

[0028] It is understood that, in this embodiment, continuous adjustment of the acquisition field of view can be achieved based on single lenses or zoom lens groups with different focal lengths. Specifically, the single-lens acquisition optical path can achieve graded adjustment of the acquisition field of view when the object distance and fiber core diameter are fixed by replacing lenses with different focal lengths; the zoom lens acquisition optical path adopts a zoom lens group composed of multiple lenses. By moving some of the lenses along the optical axis, the equivalent focal length of the system is changed, and the acquisition field of view can be continuously adjusted within a certain range when the object distance and fiber core diameter are fixed.

[0029] It should be understood that the principle behind how changing the acquisition field of view affects spectral quality lies in the fact that plasma radiation, such as... Figure 3The radiation distribution is non-uniform in space, specifically: radiation radiates from the center outwards, with high radiation intensity in the central region and low intensity in the peripheral region. When the acquisition field of view is too large, a large amount of low-intensity background radiation is introduced, reducing the signal-to-noise ratio; when the acquisition field of view is too small, only a portion of the high-radiation area is acquired, resulting in insufficient effective radiation volume and signal attenuation. Therefore, by adjusting the acquisition field of view to match the spatial range of the high-radiation region of the plasma, background interference can be suppressed while ensuring spectral intensity, thereby optimizing system performance. In this embodiment, the acquisition field of view is continuously adjusted by changing the equivalent focal length of the optical system, thus matching the acquisition field of view with the spatial distribution of plasma radiation. The principle of adjusting the acquisition field of view is as follows: changing lenses with different focal lengths or moving one lens in the lens group along the optical axis changes the equivalent focal length of the system; the change in equivalent focal length leads to a change in the system's imaging magnification, and the change in lateral magnification directly changes the size of the object-side region corresponding to the receiving surface of the spectral acquisition device, thereby achieving field of view adjustment.

[0030] It should also be noted that, for plasma, after the radiation is focused by the acquisition lens, it is coupled to a multimode fiber. The dimensions of the multimode fiber can be 600 μm core diameter and 0.22 numerical aperture, and the coupled plasma is transmitted to a single-channel spectrometer.

[0031] Furthermore, before step S20, the method further includes: when a change in a single lens is detected, performing focal plane calibration on the changed single lens; obtaining the current focal length and fixed object distance of the calibrated single lens, and calculating the target image distance based on the current focal length and the fixed object distance; calculating the lateral magnification based on the target image distance and the fixed object distance; determining a first acquisition field of view corresponding to the current focal length based on the lateral magnification and the core diameter of the multimode fiber, and determining a multi-range acquisition field of view based on each of the first acquisition fields of view.

[0032] It should be understood that for a single lens, focal plane calibration is required each time a change occurs to effectively reduce the impact of chromatic aberration on the focusing position. By changing lenses with different focal lengths, the single-lens acquisition optical path can achieve graded adjustment of the acquisition field of view while maintaining a fixed object distance and fiber core diameter, thus determining multiple acquisition field of view ranges, such as 9.8 mm, 7.2 mm, 4.6 mm, 3.3 mm, 2.0 mm, 1.35 mm, and 0.96 mm. Specifically, the single-lens acquisition optical path uses a 2-inch (approximately 50.8 mm) plano-convex lens as the acquisition lens, with a fixed object distance of 1300 mm. Acquisition lenses with focal lengths of 75, 100, 150, 200, 300, 400, and 500 mm are sequentially replaced, and the target image distance is calculated based on the current focal length and the fixed object distance. XJ = WJ×JJ / (WJ JJ).

[0033] Where XJ represents the target image distance, WJ represents the object distance, and JJ represents the focal length.

[0034] It should also be noted that after calculating the target image distance XJ, the lateral magnification is calculated in conjunction with the fixed object distance, specifically as follows: M = XJ / WJ.

[0035] Where M represents the lateral magnification, XJ represents the target image distance, and WJ represents the object distance.

[0036] Understandably, after calculating the lateral magnification, the first field of view corresponding to the current focal length can be determined by combining the core diameter of the multimode fiber, specifically: FOV1=ZJ / M.

[0037] Wherein, FOV1 represents the first field of view corresponding to the current focal length, ZJ represents the core diameter of the multimode fiber, and M represents the lateral magnification.

[0038] Furthermore, when a change in the single lens is detected, the step of calibrating the focal plane of the changed single lens includes: when a change in the single lens is detected, controlling the visible light calibration light source to couple into the multimode fiber from the output end; based on the changed single lens, controlling the light to exit from the incident end of the multimode fiber facing the single lens, and focusing the emitted visible light calibration light source onto the surface of the aluminum alloy sample to obtain the calibration light spot on the surface of the aluminum alloy sample; continuously adjusting the position of the incident end of the fiber along the optical axis until the area of ​​the calibration light spot is minimized and the sharpness characteristic value is maximized, so as to achieve focal plane calibration of the changed single lens.

[0039] It should be noted that the visible light calibration light source refers to the light source used for calibrating the focal plane of the modified single lens. It can be: a base optics, with a wavelength of 405nm, blue-violet light, and a wavelength close to the target analysis spectral line. The output end of the multimode fiber is connected to the single-channel spectrometer, and the incident end of the fiber is facing the single lens. At this time, the visible light calibration light source is coupled into the multimode fiber from the output end and emitted from the incident end of the multimode fiber facing the single lens. After passing through the single lens, it is focused on the surface of the aluminum alloy sample. At this time, it is necessary to continuously adjust the position of the incident end of the fiber along the optical axis until the area of ​​the calibration spot is minimized and the sharpness characteristic value is maximized. According to the principle of optical path reversibility, the incident end face of the fiber is precisely located at the focal plane under this focal length. The wavelength of the visible light calibration light source is close to the target analysis spectral line, which can effectively reduce the influence of chromatic aberration on the focusing position.

[0040] Furthermore, before step S20, the method further includes: when a change in the position of the concave lens in the zoom lens group is detected, performing focal plane calibration on the zoom lens group; for each distance between the concave lens and the target convex lens, determining the corresponding image plane position according to the principle of minimizing the root mean square radius of the image plane spot, and obtaining the imaging size of the plasma radiation region at the image plane position; obtaining the characteristic size of the plasma radiation region, and determining the second acquisition field of view according to the imaging size, the characteristic size, and the core diameter of the multimode fiber; and determining a multi-range acquisition field of view according to the movement range of the distance and each of the second acquisition fields of view.

[0041] It is understandable that the target convex lens can be the second convex lens. For a zoom lens group, it includes a first convex lens, a second convex lens, and a concave lens. All three lenses are coaxially arranged and can be Thorlabs plano-convex or plano-concave lenses, specifically made of UV-fused silica. The convex lens has a diameter of 2 inches, the concave lens has a diameter of 1 inch, the focal length of the first convex lens is f1 = 400 mm, the focal length of the second convex lens is f2 = 300 mm, and the focal length of the concave lens is f3 = -100 mm. The distance between the first and second convex lenses is fixed at 2 mm. The concave lens is mounted on a precision displacement stage and can move along the optical axis between the second convex lens and the fiber optic receiving end face. The distance between the concave lens and the second convex lens is l. 23 It can be continuously adjusted within the range of 110 mm to 170 mm. Focal plane calibration is also required each time the position of the concave lens in the zoom lens group changes; the calibration method is exactly the same as that for a single lens, and will not be repeated here.

[0042] It should be noted that by moving the concave lens along the optical axis and changing the relative distance between the concave lens and the two convex lenses, the equivalent focal length of the zoom lens group changes accordingly, thereby achieving continuous adjustment of the acquisition field of view. Specifically, an ICCD camera is used to capture radiation images of the plasma. Under the same laser energy and sample conditions as the spectral acquisition, the ICCD camera acquires plasma radiation images, and the delay and gate width of the ICCD camera are set according to the plasma evolution characteristics. The characteristic size D1 of the plasma radiation region is determined through the image. In the Zemax optical design software, a 4mm emitting area is set on the object surface to simulate the plasma source, and the object distance is set to 1300mm. The parameters of the zoom lens group are consistent with those used in actual applications. The distance l between the concave lens and the second convex lens is changed each time. 23 Then, the corresponding image plane position is determined according to the principle of minimizing the root mean square radius of the image plane spot, and the imaging size D2 of the plasma radiation region at the image plane position is obtained. At this time, the second acquisition field of view is determined according to the imaging size, feature size, and core diameter of the multimode fiber, specifically: FOV2 = (ZJ / D2) × D1.

[0043] Wherein, FOV2 represents the second acquisition field of view, ZJ represents the core diameter of the multimode fiber, D2 represents the imaging size, and D1 represents the feature size.

[0044] It should also be emphasized that, based on the above simulation calculations, when the object distance is 1300 mm and the core diameter of the multimode fiber is 600 μm, the distance l between the concave lens and the second convex lens is... 23 The movement range is 110mm to 170mm, enabling continuous variation of the acquisition field of view within the range of 0.8mm to 2.7mm to determine a multi-range acquisition field of view. When using a short focal length single lens, the image spot size D2 is larger due to larger aberrations, and the calculated second acquisition field of view FOV2 may be smaller than the actual field of view. In this case, the simulated spot size should be used as a reference, and the effective field of view range should be comprehensively judged by combining the single lens imaging relationship with the experimental signal change trend.

[0045] Step S30: Under the multi-range acquisition field of view, multiple laser pulses are applied to different positions on the surface of the aluminum alloy sample, and the plasma emission spectrum corresponding to each laser pulse is acquired by a single-channel spectrometer.

[0046] It should be understood that, for a single-channel spectrometer, after acquiring the plasma emission spectrum corresponding to each laser pulse, while keeping the laser parameters and detection conditions unchanged, the field of view is changed in steps within the adjustable field of view range, and refocused after each adjustment. At each focal length, laser pulses at different positions on the surface of the aluminum alloy sample are acquired and the spectrum is recorded. The cumulative number of laser pulses can be 20. This single-channel spectrometer can be an Avantes single-channel spectrometer.

[0047] Step S40: Calculate the field-of-view evaluation index of the multi-range acquisition field of view based on the plasma emission spectrum and target analysis spectral line, determine the optimal acquisition field of view based on the field-of-view evaluation index, and perform quantitative analysis of trace elements in the aluminum alloy sample under the optimal acquisition field of view.

[0048] Understandably, after acquiring the plasma emission spectra corresponding to each laser pulse, the MnI4O3.31nm spectral line is used as the target analysis line to calculate the field-of-view evaluation index for multiple acquisition fields. This evaluation index includes, but is not limited to, spectral intensity, signal-to-noise ratio, and relative standard deviation. The optimal acquisition field of view refers to the field of view that precisely covers the main part of the high-radiation region of the plasma. At this point, background interference can be effectively suppressed while ensuring spectral intensity, thus optimizing system performance. Furthermore, quantitative analysis of trace elements in aluminum alloy samples can be performed under the optimal acquisition field of view, effectively improving the efficiency and accuracy of trace element analysis.

[0049] This embodiment utilizes a laser-induced breakdown spectroscopy system to focus a high-energy laser onto the surface of a distant aluminum alloy sample, generating plasma. A multi-range acquisition field of view is determined based on single lenses or zoom lens groups with different focal lengths. The radiation emitted by the plasma is converged and coupled to a multimode fiber. Under these multi-range acquisition fields of view, multiple laser pulses are applied to different positions on the aluminum alloy sample surface, and the plasma emission spectra corresponding to each laser pulse are acquired using a single-channel spectrometer. Field of view evaluation indices are calculated based on the plasma emission spectra and target analysis lines. The optimal acquisition field of view is then determined based on these indices, and quantitative analysis of trace elements in the aluminum alloy sample is performed under this optimal field of view. By employing single lenses or zoom lens groups with different focal lengths and determining the optimal acquisition field of view based on the spatial distribution characteristics of plasma radiation, the acquisition efficiency is maximized under various optical system configurations. Furthermore, quantitative analysis of trace elements in the aluminum alloy sample is performed under the optimal acquisition field of view, effectively improving the efficiency and accuracy of trace element analysis.

[0050] In one specific implementation, this application provides steps for determining the optimal acquisition field of view and performing quantitative analysis. Please refer to... Figure 4 , Figure 4 This is the second schematic flowchart of the plasma radiation region matching method based on acquisition field-of-view adjustment provided in the embodiments of this application. Step S40 includes steps S401 to S404: Step S401: Calculate the field of view evaluation index of the multi-range acquisition field of view based on the plasma emission spectrum and target analysis spectral line, and generate the field of view curve based on the field of view evaluation index and the multi-range acquisition field of view generation index.

[0051] It should be noted that the field-of-view evaluation indicators for multi-range acquisition fields of view calculated based on laser pulses and target analysis spectral lines include, but are not limited to, spectral intensity, signal-to-noise ratio (SNR), and relative standard deviation (RSD). At this point, an indicator-field-of-view curve can be generated based on the field-of-view evaluation indicators and the multi-range acquisition field of view. See Figures 5 and 6 for details. Figure 5(a) shows a schematic diagram of the spectral intensity indicator-field-of-view curves plotted using single lenses with different focal lengths. Specifically, the horizontal axis represents focal length, and the vertical axis represents spectral intensity. Spectral intensity increases from 75mm to 300mm, and decreases from 300mm to 500mm. Figure 5(b) shows the signal-to-noise ratio, relative standard deviation (RSD), and relative standard deviation (RSD) plotted using single lenses with different focal lengths. The standard deviation index-field-of-view curve diagram is as follows: the horizontal axis represents focal length, and the vertical axis represents signal-to-noise ratio (SNR) and relative standard deviation, respectively. From 75mm to 300mm, the SNR increases and the relative standard deviation decreases. From 300mm to 500mm, the SNR decreases and the relative standard deviation increases. In summary, both spectral intensity and SNR show a trend of first increasing and then decreasing as the field of view decreases, while the relative standard deviation first decreases and then increases. At a focal length of 300mm, the spectral intensity is the highest, the SNR is the largest, and the relative standard deviation is the smallest. Figure 6(a) shows a schematic diagram of the spectral intensity index-field curve based on the zoom lens group. Specifically, the horizontal axis represents the spacing, and the vertical axis represents the spectral intensity. The spectral intensity increases from 110mm to 140mm, and decreases from 140mm to 170mm. Figure 6(b) shows a schematic diagram of the signal-to-noise ratio and relative standard deviation index-field curve based on the zoom lens group. Specifically, the horizontal axis represents the spacing, and the vertical axis represents the signal-to-noise ratio and relative standard deviation, respectively. The signal-to-noise ratio increases from 110mm to 140mm, and the relative standard deviation decreases from 150mm to 170mm. In summary, both the spectral intensity and the signal-to-noise ratio show a trend of first increasing and then decreasing with the increase of the field of view, while the relative standard deviation first decreases and then increases. The spectral intensity is the highest when the spacing is 140mm, and the signal-to-noise ratio is the largest and the relative standard deviation is the smallest when the spacing is 150mm.

[0052] Step S402: Analyze the trend of index change in the index-field curve.

[0053] Step S403: Determine the optimal field of view evaluation index that meets the requirements based on the trend analysis results, and take the acquisition field of view corresponding to the optimal field of view evaluation index as the optimal acquisition field of view.

[0054] It should be understood that after analyzing the trend of the index-field-of-view curve, the optimal field-of-view evaluation index needs to be determined based on the trend analysis results. For example, if the trend analysis shows that both spectral intensity and signal-to-noise ratio increase first and then decrease as the field of view decreases, while the relative standard deviation decreases first and then increases, then the optimal field-of-view evaluation index is determined to be: simultaneously optimal at a focal length of 300 mm, corresponding to a field of view of approximately 2.0 mm, i.e., highest spectral intensity, highest signal-to-noise ratio, and lowest relative standard deviation. A field of view larger or smaller than this value leads to performance degradation; therefore, the optimal field of view is determined to be 2.0 mm. Alternatively, at a spacing of l... 23 The optimal acquisition field of view is achieved at approximately 140 mm, corresponding to a field of view of approximately 1.7 mm. This optimal field of view corresponds to the optimal matching state between the high-radiation region of the plasma and the acquisition area.

[0055] It should be noted that the optimal field of view determined above is basically consistent, indicating that the optimal field of view is determined by the spatial distribution characteristics of plasma radiation and is independent of the specific optical system used, reflecting the universality of the technical solution of this embodiment.

[0056] Step S404: Quantitative analysis of trace elements in the aluminum alloy sample is performed under the optimal acquisition field of view.

[0057] Further, step S404 includes: acquiring the main body of the high-radiation region of the plasma; determining the coverage area of ​​the optimal acquisition field of view; when the coverage area exactly covers the main body, calculating the field of view analysis index of the optimal acquisition field of view and other acquisition fields of view respectively; when the field of view analysis index determines that the quantitative analysis stability of the optimal acquisition field of view is higher than that of the other acquisition fields of view, performing quantitative analysis of trace elements in the aluminum alloy sample under the optimal acquisition field of view.

[0058] It should be noted that, in order to verify the accuracy of the optimal acquisition field of view in this embodiment, it is also necessary to determine the main part of the high-radiation region of the plasma and the coverage area of ​​the optimal acquisition field of view, and to determine whether the coverage area exactly covers the main part. If so, it indicates that the background interference can be effectively suppressed while ensuring the spectral intensity, thereby achieving the optimization of system performance.

[0059] It should be understood that, in addition to this, the field of view of the zoom system of the zoom lens group can be fixed at the optimal field of view of 1.7 mm to perform LIBS spectral acquisition on a group of aluminum alloy standard samples, in which the Mn content ranges from 0.0019% to 0.066%, and 20 laser pulses are acquired at different positions for each sample. A calibration curve is established with the Mn I 403.31 nm as the target analytical line, and the coefficient of determination R² is 0.99, and the mean relative standard deviation RSD is 16.8%. This indicates that under this optimal field of view, the system can achieve good quantitative analysis accuracy and repeatability of trace elements in aluminum alloys. Therefore, quantitative analysis of trace elements in aluminum alloy samples can be performed under the optimal field of view, realizing high-sensitivity, high signal-to-noise ratio, and high-stability long-distance laser-induced breakdown spectroscopy detection, thereby effectively improving the efficiency and accuracy of trace element analysis.

[0060] This embodiment calculates the field-of-view evaluation index of the multi-range acquisition field of view based on the plasma emission spectra and target analysis spectral lines, and generates an index-field-of-view curve based on the field-of-view evaluation index and the multi-range acquisition field of view; analyzes the trend of index change of the index-field-of-view curve; determines the optimal field-of-view evaluation index that meets the requirements based on the trend analysis results, and takes the acquisition field of view corresponding to the optimal field-of-view evaluation index as the optimal acquisition field of view; and performs quantitative analysis of trace elements in the aluminum alloy sample under the optimal acquisition field of view. Through the above method, based on the field-of-view evaluation index and the index-field-of-view curve generated by the multi-range acquisition field of view, and analyzing the trend of index change of the index-field-of-view curve, the spectral intensity and signal-to-noise ratio both show a trend of first increasing and then decreasing as the field of view shrinks, while the relative standard deviation first decreases and then increases. At this point, based on the trend analysis results of the index-field-of-view curve, the optimal field-of-view evaluation index with the highest spectral intensity, the highest signal-to-noise ratio, and the lowest relative standard deviation is determined, and quantitative analysis of trace elements in the aluminum alloy sample is performed under the optimal acquisition field of view, thereby effectively improving the efficiency and accuracy of trace element analysis.

[0061] The plasma radiation region matching device based on acquisition field-of-view adjustment provided in this application is described below. The plasma radiation region matching device based on acquisition field-of-view adjustment described below can be referred to in correspondence with the plasma radiation region matching method based on acquisition field-of-view adjustment described above. Please refer to... Figure 7 , Figure 7 This is a schematic diagram of the module structure of the plasma radiation region matching device based on acquisition field-of-view adjustment provided in this application embodiment, including: The generation module T10 is used to focus a high-energy laser onto the surface of an aluminum alloy sample at a distance based on a laser-induced breakdown spectroscopy system to generate plasma.

[0062] The determination module T20 is used to determine a multi-range acquisition field of view based on single lenses or zoom lens groups with different focal lengths, to converge the radiation light emitted by the plasma, and to couple the converged plasma radiation light to a multimode optical fiber.

[0063] The acquisition module T30 is used to apply multiple laser pulses to different positions on the surface of the aluminum alloy sample under the multi-range acquisition field of view, and to acquire the plasma emission spectrum corresponding to each laser pulse through a single-channel spectrometer.

[0064] The determining module T20 is also used to calculate the field evaluation index of the multi-range acquisition field of view based on each of the plasma emission spectra and target analysis spectral lines, and to determine the optimal acquisition field of view based on the field evaluation index, and to perform quantitative analysis of trace elements in the aluminum alloy sample under the optimal acquisition field of view.

[0065] This embodiment utilizes a laser-induced breakdown spectroscopy system to focus a high-energy laser onto the surface of a distant aluminum alloy sample, generating plasma. A multi-range acquisition field of view is determined based on single lenses or zoom lens groups with different focal lengths. The radiation emitted by the plasma is converged and coupled to a multimode fiber. Under these multi-range acquisition fields of view, multiple laser pulses are applied to different positions on the aluminum alloy sample surface, and the plasma emission spectra corresponding to each laser pulse are acquired using a single-channel spectrometer. Field of view evaluation indices are calculated based on the plasma emission spectra and target analysis lines. The optimal acquisition field of view is then determined based on these indices, and quantitative analysis of trace elements in the aluminum alloy sample is performed under this optimal field of view. By employing single lenses or zoom lens groups with different focal lengths and determining the optimal acquisition field of view based on the spatial distribution characteristics of plasma radiation, the acquisition efficiency is maximized under various optical system configurations. Furthermore, quantitative analysis of trace elements in the aluminum alloy sample is performed under the optimal acquisition field of view, effectively improving the efficiency and accuracy of trace element analysis.

[0066] It is understood that the detailed functional implementation of each of the above modules can be found in the description of the aforementioned method embodiments, and will not be repeated here.

[0067] It should be understood that the above-described device is used to execute the methods in the above embodiments. The implementation principle and technical effect of the corresponding program modules in the device are similar to those described in the above methods. The working process of the device can be referred to the corresponding process in the above methods, and will not be repeated here.

[0068] Based on the methods in the above embodiments, this application provides an electronic device, please refer to... Figure 8 , Figure 8This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application.

[0069] It should be noted that the system may include: a processor 10, a communications interface 20, a memory 30, and a communication bus 40. The processor 10, communications interface 20, and memory 30 communicate with each other via the communication bus 40. The processor 10 can invoke logical instructions stored in the memory 30 to execute the methods described in the above embodiments.

[0070] Furthermore, the logical instructions in the aforementioned memory 30 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application.

[0071] Based on the methods in the above embodiments, this application provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0072] Based on the methods in the above embodiments, this application provides a computer program product that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0073] It is understood that the processor in the embodiments of this application can be a central processing unit, or it can be other general-purpose processors, digital signal processors, application-specific integrated circuits, field-programmable gate arrays, or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor can be a microprocessor or any conventional processor.

[0074] The method steps in this application embodiment can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor.

[0075] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. Those skilled in the art will readily understand that the above descriptions are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A plasma radiation region matching method based on acquisition field-of-view adjustment, characterized in that, include: Based on a laser-induced breakdown spectroscopy system, a high-energy laser is focused onto the surface of an aluminum alloy sample at a distance to generate plasma; A multi-range acquisition field of view is determined based on single lenses or zoom lens groups with different focal lengths, the radiation light emitted by the plasma is converged, and the converged plasma radiation light is coupled to a multimode fiber. Under the multi-range acquisition field of view, multiple laser pulses are applied to different positions on the surface of the aluminum alloy sample, and the plasma emission spectrum corresponding to each laser pulse is acquired by a single-channel spectrometer. The field-of-view evaluation index of the multi-range acquisition field of view is calculated based on the plasma emission spectrum and target analysis spectral lines, and the optimal acquisition field of view is determined based on the field-of-view evaluation index. Under the optimal acquisition field of view, the trace elements in the aluminum alloy sample are quantitatively analyzed.

2. The plasma radiation region matching method as described in claim 1, characterized in that, Before the steps of determining a multi-range acquisition field of view based on single lenses or zoom lens groups with different focal lengths, focusing the radiation light emitted by the plasma, and coupling the focused plasma radiation light to a multimode fiber, the method further includes: When a change is detected in a single lens, the focal plane of the changed single lens is calibrated. Obtain the current focal length and fixed object distance of the calibrated single lens, and calculate the target image distance based on the current focal length and the fixed object distance; Calculate the lateral magnification based on the target image distance and the fixed object distance; A first acquisition field of view corresponding to the current focal length is determined based on the lateral magnification and the core diameter of the multimode fiber, and a multi-range acquisition field of view is determined based on each of the first acquisition fields of view.

3. The plasma radiation region matching method as described in claim 2, characterized in that, The step of calibrating the focal plane of the changed single lens when a change is detected includes: When a change is detected in a single lens, the visible light calibration light source is controlled to couple into the multimode fiber from its output end. Based on the modified single lens, the light emitted from the incident end of the multimode fiber facing the single lens is controlled, and the emitted visible light calibration light source is focused on the surface of the aluminum alloy sample to obtain the calibration light spot on the surface of the aluminum alloy sample. The position of the optical fiber incident end is continuously adjusted along the optical axis until the area of ​​the calibration spot is minimized and the sharpness characteristic value is maximized, so as to achieve focal plane calibration of the changed single lens.

4. The plasma radiation region matching method as described in claim 1, characterized in that, Before the steps of determining a multi-range acquisition field of view based on single lenses or zoom lens groups with different focal lengths, focusing the radiation light emitted by the plasma, and coupling the focused plasma radiation light to a multimode fiber, the method further includes: When a change in the position of the concave lens in the zoom lens group is detected, the zoom lens group is calibrated to the focal plane. For each distance between the concave lens and the target convex lens, the corresponding image plane position is determined according to the principle of minimizing the root mean square radius of the image plane spot, and the imaging size of the plasma radiation region at the image plane position is obtained. The characteristic dimensions of the plasma radiation region are obtained, and a second acquisition field of view is determined based on the imaging size, the characteristic dimensions, and the core diameter of the multimode fiber. A multi-range acquisition field of view is determined based on the movement range of the spacing and each of the second acquisition fields of view.

5. The plasma radiation region matching method according to any one of claims 1 to 4, characterized in that, The steps of calculating the field-of-view evaluation index of the multi-range acquisition field of view based on the plasma emission spectra and target analysis spectral lines, determining the optimal acquisition field of view based on the field-of-view evaluation index, and performing quantitative analysis of trace elements in the aluminum alloy sample under the optimal acquisition field of view include: The field-of-view evaluation index of the multi-range acquisition field of view is calculated based on the plasma emission spectrum and target analysis spectral line, and the field-of-view generation index-field curve is calculated based on the field-of-view evaluation index and the multi-range acquisition field of view generation index. Analyze the trend of index change in the index-field-of-view curve; Based on the trend analysis results, the optimal field of view evaluation index that meets the requirements is determined, and the acquisition field of view corresponding to the optimal field of view evaluation index is taken as the optimal acquisition field of view. Quantitative analysis of trace elements in aluminum alloy samples was performed under the optimal acquisition field of view.

6. The plasma radiation region matching method as described in claim 5, characterized in that, The step of quantitatively analyzing trace elements in the aluminum alloy sample under the optimal acquisition field of view includes: The main part for acquiring the high-radiation region of plasma; Determine the coverage area of ​​the optimal field of view; When the coverage area exactly covers the main body, the field analysis indexes of the optimal acquisition field of view and other acquisition fields of view are calculated respectively. When the quantitative analysis stability of the optimal acquisition field of view is determined to be higher than that of the other acquisition fields of view based on the field of view analysis index, the trace elements in the aluminum alloy sample are quantitatively analyzed under the optimal acquisition field of view.

7. A plasma radiation region matching device based on acquisition field-of-view adjustment, characterized in that, include: The generation module is used to focus a high-energy laser onto the surface of an aluminum alloy sample at a distance based on a laser-induced breakdown spectroscopy system to generate plasma. The determination module is used to determine a multi-range acquisition field of view based on single lenses or zoom lens groups with different focal lengths, converge the radiation light emitted by the plasma, and couple the converged plasma radiation light to a multimode fiber. The acquisition module is used to apply multiple laser pulses to different positions on the surface of the aluminum alloy sample under the multi-range acquisition field of view, and to acquire the plasma emission spectrum corresponding to each laser pulse through a single-channel spectrometer. The determining module is further configured to calculate the field-of-view evaluation index of the multi-range acquisition field of view based on each of the plasma emission spectra and target analysis spectral lines, and determine the optimal acquisition field of view based on the field-of-view evaluation index, and perform quantitative analysis of trace elements in the aluminum alloy sample under the optimal acquisition field of view.

8. An electronic device, characterized in that, include: At least one memory for storing computer programs; At least one processor is configured to execute a program stored in the memory, wherein when the program stored in the memory is executed, the processor is configured to perform the method as described in any one of claims 1-6.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is run on the processor, it causes the processor to perform the method as described in any one of claims 1-6.

10. A computer program product, characterized in that, When the computer program product is run on a processor, the processor causes the processor to perform the method as described in any one of claims 1-6.

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