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Feasibility study and demonstration of cleaning with laser adaptively by novel use of sensors
摘要： Surface cleaning is an essential step within the manufacturing process that ensures and enhances the integrity of the final component. Conventional surface cleaning methods have various shortfalls leading to the need for a more controllable surface cleaning methods such as laser cleaning. By utilising the principle behind laser induced breakdown spectroscopy (LIBS), an economical inline monitoring system is implemented in a laser cleaning cell, to achieve a closed-loop laser coating removal from tungsten carbide substrate. Cutting tests were performed on the re-coated laser coating removed inserts showing similar performance as compared to the as-received coated inserts.
关键词： LIBS,cutting tools,inline monitoring,Laser cleaning,closed-loop
更新于2025-09-16 10:30:52
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Ultrafast Elemental Mapping of Platinum Group Elements and Mineral Identification in Platinum-Palladium Ore Using Laser Induced Breakdown Spectroscopy
摘要： This paper demonstrates the capability of performing an ultrafast chemical mapping of drill cores collected from a platinum/palladium mine using laser‐induced breakdown spectroscopy (LIBS). A scan of 40 mm × 30 mm was performed, using a commercial LIBS analyzer, onto the flat surface of a drill core with a scanning speed of 1000 Hz, and a spatial resolution of 50 μm, in about 8 min. Maps of the scanned areas for seven chemical elements (platinum, palladium, nickel, copper, iron, silicon, and magnesium), as well as a single map including the seven elements altogether, were then generated using the proprietary software integrated into the LIBS analyzer. Based on the latter image, seven minerals were identified using the principal component analysis (PCA) and correlations with the elemental maps.
关键词： laser induced breakdown spectroscopy (LIBS),mineral identification,platinum‐group elements (PGE),principal component analysis (PCA),scanning speed at 1000 Hz
更新于2025-09-16 10:30:52
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Laser-Induced Breakdown Spectroscopy Assisted by Machine Learning for Plastics/Polymers Identification
摘要： In the present work, Laser-Induced Breakdown Spectroscopy (LIBS) is used for the discrimination/identification of different plastic/polymeric samples having the same polymeric matrix but containing different additives (as e.g., fillers, flame retardants, etc.). For the classification of the different plastic samples, some machine learning algorithms were employed for the analysis of the LIBS spectroscopic data, such as the Principal Component Analysis (PCA) and the Linear Discriminant Analysis (LDA). The combination of LIBS technique with these machine learning algorithmic approaches, in particular the latter, provided excellent classification results, achieving identification accuracies as high as 100%. It seems that machine learning paves the way towards the application of LIBS technique for identification/discrimination issues of plastics and polymers and eventually of other classes of organic materials. Machine learning assisted LIBS can be a simple to use, efficient and powerful tool for sorting and recycling purposes.
关键词： laser-induced breakdown,polymers,LIBS,machine learning,identification of polymers,laser produced plasmas
更新于2025-09-16 10:30:52
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Honey exposed to laser-induced breakdown spectroscopy for chaos-based botanical classification and fraud assessment
摘要： Given that honey is among the top ten foods with the highest adulteration rate in the European Union, in this research, a tool has been developed to tackle this malpractice. The combination of laser-induced breakdown spectroscopy (LIBS) and chaotic parameters has been employed to classify six European honeys of different botanical origins as well as detect samples containing the usually elusive rice syrup adulteration in weight concentrations as low as 2 %. The profiles of the LIBS emission spectra can be used to faithfully classify honey in terms of botanical origin by combining information extracted directly from the spectra with simple linear modeling. In contrast, the detection of low amounts of rice syrup in honey is not as straightforward, which is why algorithms based on chaotic parameters such as shifted (lag-k) autocorrelation coefficients were employed to extract underlying information representative of adulterated samples. Since these algorithms are capable of detecting slight changes in the composition of honeys, it has been possible to identify these adulterations with a success rate greater than 90 % when samples from honeys of different botanical origins are combined into the same model, and over 95 % when individual honey types are analyzed.
关键词： Chaotic Parameters,Classification,LIBS,Adulteration,Botanical Origin,Honey
更新于2025-09-16 10:30:52
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Laser-induced breakdown spectroscopy for food authentication
摘要： With the globalisation of food markets, food authentication has become a significant concern worldwide to ensure food safety and to avoid origin and quality fraud. A multi-elemental fingerprint is a powerful tool for detection of adulterants and geographical origin of foods. Laser-induced breakdown spectroscopy (LIBS) is a promising technique that can provide a mineral fingerprint of food products. LIBS allows a rapid, high-throughput, micro-destructive and multi-elemental analysis of a wide range of samples type. It has already been demonstrated by several authors that LIBS can be successfully used for food authentication. Although LIBS shows excellent potential for at-line or portable applications, improvement in sensitivity of trace elements detection, sample preparation, data analysis and instrument miniaturisation are needed.
关键词： LIBS,Laser-induced breakdown spectroscopy,multi-elemental analysis,food authentication,fraud detection
更新于2025-09-16 10:30:52
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Mineral carbonate dissolution with increasing CO2 pressure measured by underwater laser induced breakdown spectroscopy and its application in carbon sequestration
摘要： In this study, the ability of laser-induced breakdown spectroscopy (LIBS) to measure the in situ aqueous dissolution of various mineral carbonates with increasing CO2 pressure was examined. Dissolution experiments included four geologically common mineral carbonates (CaCO3, MgCO3, MnCO3, SrCO3) and the CO2 pressure ranged from ambient to 250 bar. The ensuing plasma emission was spectrally analyzed, and the intensities of Ca, Mg, Mn, and Sr emission lines were used to monitor the respective metal cations released to the aqueous solution. The strong emission lines of Ca (Ca II 393.36, Ca II 396.84, Ca I 422.67 nm), Mg (unresolved magnesium doublet: Mg I 383.230, Mg I 383.829 nm), Mn (unresolved manganese triplet: Mn I 403.076, Mn I 403.307, Mn I 403.449 nm), and Sr (Sr II 407.77, Sr II 421.55, Sr I 460.73 nm) were identified in the spectra. The amounts of metals released from their respective carbonates were estimated at different time intervals following the CO2 injection (5 m, 1, 2, 3, 4, 24 h) and at different pressures (50, 100, 150, 200, 250 bar) using calibration models developed at corresponding pressure settings. The results demonstrated that the pressure-induced dissolution of all carbonates was consistent with their expected and selective pH-dependent solubility. The dissolution rate of CaCO3, MgCO3, and SrCO3 was found to be higher than that of MnCO3. The dissolution of constituents in a Mt. Simon sandstone associated with a deep saline reservoir at elevated CO2 pressure was also studied and Ca release was quantified. The results demonstrated that real-time monitoring of carbonate dissolution by LIBS may provide a useful indirect detection system indicative of CO2 leakage from geologic carbon storage sites.
关键词： Monitoring of carbonate dissolution by LIBS,Underwater LIBS for CO2 leakage detection,Carbonate dissolution
更新于2025-09-12 10:27:22
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An original LIBS system based on TEA CO2 laser as a tool for determination of glass surface hardness
摘要： This study was carried out to examine the applicability of original laser-induced breakdown spectroscopy (LIBS) setup for determination of the surface hardness of lead glass as a function of its chemical composition. For this purpose, a set of five lead glass samples with different amount of ZrO2 was prepared. The LIBS measurements were carried out using TEA CO2 laser in the air at atmospheric pressure and without sample preparation. A ratio of the intensity between the Zr(II) 355.66 nm and Zr(I) 360.12 nm emission lines has been used to examine the hardness of the material. In addition, the surface hardness of glass samples was determined by Vickers’s indentation tests. Obtained results indicate a linear relationship of the measurements of hardness in glass samples between the LIBS and Vickers method. To show that LIBS based on TEA CO2 laser is an almost nondestructive technique, profilometric surface analysis was used. The proposed LIBS system is suitable not only for a spectrochemical analysis but also as an easy to use and cost-effective way to measure the surface hardness for all types and shapes of glass samples which are in some cases difficult to examine by standard Vicker’s method.
关键词： surface hardness,lead glass,ZrO2,LIBS,TEA CO2 laser
更新于2025-09-12 10:27:22
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Simultaneous measurements of fuel concentration and temperature in gas jets by laser induced breakdown spectroscopy
摘要： Laser induced breakdown spectroscopy (LIBS) enables quantitative measurements of the equivalence ratio in flames, spray and gas jets. Although there are always considerable temperature differences between the calibrations and the LIBS measurements in flames and fuel jets, the temperature effects on LIBS were rarely mentioned and not corrected in the previous LIBS measurements. In this study, a novel method to simultaneously measure the equivalence ratio and the gas temperature by LIBS in a single laser shot is proposed. This method can correct the temperature effects based on the linear correlation between the peak intensity ratio (PIR) of atomic lines and the gas temperature. The PIR of H656/N746 and the full width at half maximum (FWHM) of H656 are employed to establish calibration curves with the equivalence ratio and the gas temperature, respectively, and both of calibrations show high coefficients of determination (R2). Then, the measurement accuracy and precision of the proposed method are discussed in detail. The total uncertainties in measurements of equivalence ratio and gas temperature are estimated by 5.6% and 5.8%, respectively. Finally, the simultaneous measurements of equivalence ratios and gas temperatures in methane jets at different positions and at different injection pressures are conducted. The comparison of equivalence ratios before and after correction of the temperature effects indicates that the accuracy of the fuel concentration measurements by LIBS would be remarkably degraded if the temperature variations were neglected.
关键词： Measurement uncertainties,Laser-induced breakdown spectroscopy (LIBS),Equivalence ratio,Gas temperature,Full width at the half maximum (FWHM)
更新于2025-09-12 10:27:22
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Investigation of compositional variations in chromitite ore with imaging Laser Induced Breakdown Spectroscopy and Spectral Angle Mapper classification algorithm
摘要： This paper focusses on the applicability of the Spectral Angle Mapper (SAM) algorithm for supervised classification of imaging Laser Induced Breakdown Spectroscopy (LIBS) data. Our main objective is to investigate variations in the chemical/mineralogical composition of complex ore from the sub-millimetre to the metre scale, which may offer novel and barely investigated interpretation opportunities for exploration purposes. This research is based on coarse chromitite ore from Merensky Reef, represented by a drill core and a small section through the upper chromitite layer. Detailed LIBS-based imaging measurements were accompanied by space-resolved reference measurements based on SEM/MLA and EDXRF, as well as bulk chemical analyses for multiple core slices. The SAM algorithm was applied for classification of LIBS hyperspectral images with respect to differences in mineral chemistry. Our investigations focused on the pre-processing of LIBS spectra prior to SAM classification, on spectral library development, as well as on the validation of the classified data. The SAM classification algorithm, which is solely based on ratios between spectral intensities, was found insensitive to normal shot-to-shot plasma variations and to chemically induced matrix effects. However, the algorithm may become inaccurate at low signal to noise ratios, at the border between different mineral grains (mixed spectra), or when classifying chemically similar phases such as pyrite and pyrrhotite. The extent of mixed spectra depends both on the size of the mineral grains as well as on the spot size of the LIBS laser. The SAM algorithm was successfully applied for classification of several base metal sulphides, rock-forming minerals, accessory minerals, as well as several mixed phases representing the main borders between different mineral grains. The resulting classified LIBS image shows the spatial distribution of the different phases, which is in very good agreement with the space-resolved reference measurements based on EDXRF and SEM/MLA. The results also highlight the extremely heterogeneous distribution of e.g. the sulphide phases in the investigated core piece. The applicability of the LIBS-SAM classification image for estimating metal concentrations based on point counting has been explored for Cu, Ni, S, and Cr. We conclude that this approach, when applied on sufficiently large surfaces, enables semi-quantitative data analysis, as well as the possible detection of trace elements (e.g. Pt, Pd) that occur in very small nuggets.
关键词： Chromitite Ore,Core Scanner,Spectral Angle Mapper,Geochemical Exploration,Laser Induced Breakdown Spectroscopy (LIBS),Mineral Classification
更新于2025-09-12 10:27:22
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Comparison of Calibration Approaches in Laser-Induced Breakdown Spectroscopy for Proximal Soil Sensing in Precision Agriculture
摘要： The lack of soil data, which are relevant, reliable, a?ordable, immediately available, and su?ciently detailed, is still a signi?cant challenge in precision agriculture. A promising technology for the spatial assessment of the distribution of chemical elements within ?elds, without sample preparation is laser-induced breakdown spectroscopy (LIBS). Its advantages are contrasted by a strong matrix dependence of the LIBS signal which necessitates careful data evaluation. In this work, di?erent calibration approaches for soil LIBS data are presented. The data were obtained from 139 soil samples collected on two neighboring agricultural ?elds in a quaternary landscape of northeast Germany with very variable soils. Reference analysis was carried out by inductively coupled plasma optical emission spectroscopy after wet digestion. The major nutrients Ca and Mg and the minor nutrient Fe were investigated. Three calibration strategies were compared. The ?rst method was based on univariate calibration by standard addition using just one soil sample and applying the derived calibration model to the LIBS data of both ?elds. The second univariate model derived the calibration from the reference analytics of all samples from one ?eld. The prediction is validated by LIBS data of the second ?eld. The third method is a multivariate calibration approach based on partial least squares regression (PLSR). The LIBS spectra of the ?rst ?eld are used for training. Validation was carried out by 20-fold cross-validation using the LIBS data of the ?rst ?eld and independently on the second ?eld data. The second univariate method yielded better calibration and prediction results compared to the ?rst method, since matrix e?ects were better accounted for. PLSR did not strongly improve the prediction in comparison to the second univariate method.
关键词： laser-induced breakdown spectroscopy,soil nutrients,elemental composition,proximal soil sensing,LIBS
更新于2025-09-12 10:27:22