Self-absorption reduction in laser-induced breakdown spectroscopy using laser-stimulated absorption: publisher's note.

This publisher's note contains corrections to Opt. Lett.40, 5224 (2015).OPLEDP0146-959210.1364/OL.40.005224.

Diagnosis of nasopharyngeal carcinoma from serum samples using hyperspectral imaging combined with a chemometric method.

Diagnosing nasopharyngeal carcinoma (NPC) is a significant challenge because of the highly complex process. We proposed an approach to diagnose NPC serum using a combination of hyperspectral imaging and weight-based principal component analysis. Samples were prepared by pressing boric acid into pellets for use as the sera substrate. The sera, collected from 100 healthy volunteers and 60 NPC patients, was dripped onto the surface of the substrate for hyperspectral imaging. The characteristic spectral bands were selected based on the variable weight obtained from a support vector machine (SVM) model, using principal component analysis (PCA) to reduce the dimension in the extracted bands. Obtained results show that the accuracy rate, sensitivity, and specificity between the NPC sera and the sera of the healthy controls reached extremely high levels of 99.15%, 98.79%, and 99.36%, respectively. For the model's consistency evaluation, we found that the Kappa and area under the curve (AUC) of the receiver operating characteristic (ROC) curve were 0.99 and 0.98, respectively. These results suggest that the developed approach could serve as a noninvasive diagnostic and screening tool for highly accurate and consistent detection of NPC. Hence, a combination of hyperspectral imaging (HSI) and a weighted principal component analysis (WPCA)-SVM model represents a powerful and promising tool for NPC diagnosis.

Accuracy and stability improvement for meat species identification using multiplicative scatter correction and laser-induced breakdown spectroscopy.

An efficient method has been developed to identify meat species by using laser-induced breakdown spectroscopy (LIBS). To improve the accuracy and stability of meat species identification, multiplicative scatter correction (MSC) was adopted to first pretreat the spectrum for correction of spectrum scatter. Then the corrected spectra were identified by using the K-nearest neighbor (KNN) model. The results showed that the identification rate improved from 94.17% to 100% and the prediction coefficient of variance (CV) decreased from 5.16% to 0.56%. This means that the accuracy and stability of meat species identification using MSC and LIBS simultaneously improved. In light of the findings, the proposed method can be a valuable tool for meat species identification using LIBS.

Self-absorption reduction in laser-induced breakdown spectroscopy using laser-stimulated absorption.

The self-absorption effect is one of the main bottlenecks for the laser-induced breakdown spectroscopy (LIBS) technique. In this Letter, LIBS assisted by laser-stimulated absorption (LSA-LIBS) is proposed to solve this problem. The process of LSA in self-absorption reduction is discussed and confirmed. The serious self-absorption phenomena of spectral lines (K, Mn, and Al) were not observed in LSA-LIBS. The full width at half-maximum (FWHM) of K, Mn, and Al was reduced by about 58%, 25%, and 52%, respectively. The results demonstrate the capability of this approach to self-absorption reduction in the LIBS technique.

[Research Progress on Laser-Induced Breakdown Spectroscopy Based on Resonance Excitation].

Laser-induced breakdown spectroscopy (LIBS), a new kind of atomic spectrum analysis technology, has attracted much atterition of the researchers due to its characteristics of real-time, simultaneous multi-element analysis, and no sample preparation. However, the poor analytical sensitivity has been an important factor that restricts the development of this technology. LIBS based on resonance excitation combines atomic fluorescence spectroscopy and laser-induced breakdown spectroscopy and selectively excites the target elements. In this way, the analytical sensitivity of LIBS can be improved substantially and its application for trace elements detection is greatly expanded. In this paper, the research development of LIBS based on resonance excitation is summarized. The generation of atomic, fluorescence spectrum in laser-induced plasma, the typical classification and the basic principle of LIBS based on resonance. excitation are introduced. The influence of ablation laser energy, resonant laser energy and wavelength, delay between the ablation laser and the resonant laser, and the gate width on spectral enhancement are analyzed in detail. The application status and deficiencies of LIBS based on resonance excitation in the fields of metallurgy, environmental monitoring and isotope detection are elaborated. Future prospects of LIBS based on resonance excitation are also described.

[Quantitative analysis of vanadium and titanium in steel samples using LIBS].

The concentrations of vanadium and titanium elements in the steel samples were quantitatively analyzed by Laser-induced breakdown spectroscopy technique in the present paper. The lines of V (VI: 440.85 nm) and Ti (Ti I: 334.19 nm) were chosen as the quantitative analysis spectral lines, while spectral line of Fe (Fe I: 438.35 nm) was chosen as the internal calibration line due to it being the matrix element. Then the calibration curves of V and Ti elements were established with basic calibration method and internal calibration method respectively to quantitatively analyze the concentrations of vanadium and titanium elements in steel. The experimental results showed that the fitting correlation coefficient (R2) of vanadium and titanium elements are 0.9875 and 0.9909 when using basic calibration method, and their maximum relative errors of measurement are 11.09% and 4% respectively; while the fitting correlation coefficient (R2) of vanadium and titanium elements reachs 0.9952 and 0.9921 respectively when using internal calibration method, at the same time, the relative errors of measurement for vanadium and titanium elements were decreased to be lower than 4%. The results of this study demonstrated that the concentration measurement of vanadium and titanium elements in the steel was more suitable with internal calibration method in laser-induced breakdown spectroscopy.