Systematic Optimization Of Handheld LIBS And Development Of Software For Geological Sample Analysis

Recently,Laser Induced Breakdown Spectroscopy(LIBS)is becoming more and more attention in geology fields for its unique advantages of simultaneous multi-element analysis,on-line,speed,in-situ analysis and the portable even handheld instruments due to the development of laser source and mini-spectrometers.So LIBS technique has been widely used in environment Monitor,geology research,biomedical and so on.In LIBS control system,a high power laser radiation source providing pulses is used to burn sample's surface to generate a plasma.A portion of the emission spectrum is recorded,the qualitative and quantitative analysis of the sample composition related to the relative intensity and wavelength information of the spectrum.The instrument based on LIBS technology is mainly composed of a high power laser source,spectrometer,optical device,delay device and computer.It has the advantages of simple principle,convenient operation and so on.It has been attracted more and more attention by researchers.Based on the laboratory desktop LIBS analysis & test software,it needs to optimize the control system which makes the measurement and analysis to suit the handheld LIBS instrument.At the same time,according to the specific application fields such as geological exploration,the control system add the new functions of data processing algorithm module,making it better to service the geological workers and improve work efficiency.The main research contents are as follows:(1)Optimize the desktop LIBS control system to make it suitable for handheld LIBS spectrum analyzerHandheld LIBS instrument is not only smaller in size and volume than the bench LIBS spectrum analyzer,also differences in the way of communication of each component.Based on the advatages of the original LIBS control system,when the parts of the models change,the corresponding components can be expanded according to the interface,and then can be optimized.Handheld LIBS instrument is used independently developed laser providing sample burning laser source;the spectrometer collect the plasma emission,all of those lay the foundation for further data analysis.In order to reduce the background spectrum,the delay time is delayed by the software and then the spectrometer is used to acquire the spectral emission line.Furthermore,the handheld LIBS software is optimized and improved in man-machine interface.Through the software test,handheld LIBS analysis software can measure and control system of LIBS after optimization,meeting the control requirements.(2)Using LIBS technology to analyze the spectral characteristics of geological sample and using pattern recognition to classification and software development.Study the spectral characteristics of LIBS spectra of the geological samples obtained a large number of emission lines,including the main elements and trace elements,and the spectral lines had good noise ratio.Due to sample matrix,the content of different elements,different materials has different LIBS spectrum.The main components of each sample were extracted by unsupervised principal component analysis(PCA).Through Matlab platform and C # language for mixed programming,the main components of the unknown samples were extracted and the categories were determined.(3)Study on quantitative method of sample elements and software developmentStudy the algorithm model suitable for quantitative analysis of geological sample were provided methods support and data processing software.Based on the partial least squares regression(PLS-DA)method,it can effectively solve the problem that the number of samples is less than the number of variables and has good fitting performance as the input variable.Through the Matlab platform to generate the PLS-DA function as DLL dynamic link library.Based on the NET framework developed COM component interface,the use of C # language call DLL and MWArray.dll to achieve mixed programming and improve the software development speed and efficiency.The handheld LIBS measurement and control system embedded in the data processing functions can effectively use the LIBS spectral data for field analysis.Based on the pattern recognition and partial least squares regression(PLS-DA)algorithm,the geological samples are measured and analyzed more fastly and accurately.The handheld LIBS measurement and control system has good stable performance,fault tolerance and recovery capability.The analysis results of the control & test system for handheld LIBS can meet the requirements of the current rapid real-time measurement.