Design Of Laser-induced Breakdown Spectrometer And Its Application

Laser-Induced Breakdown Spectroscopy(LIBS)is an emerging technology in material detection.The elements of the sample could be detected without tedious preparations.The samples could be analyzed in any physical states,such as solid,liquid,gas,conductor,non-conductor and high temperature resistant material.Hence,LIBS is also known as an "universal" detection technology,and has wild application prospects in the fields of industrial production control,environmental testing,aerospace and so on.At present,the demands for LIBS instruments are greatly growing in the domestic market.However,the experimental or commercial LIBS systems rely heavily on imported products.In this paper,a LIBS system based on high-resolution fiber spectrometer with CCD as detectors was designed and demonstrated.Additionally,the method of reconstructing the spectrum based on the deconvolution algorithm was discussed to improve the luminous flux.In the first section,the applications,merits and demerits of LIBS technology and the development of domestic and overseas LIBS instruments were introduced.In the theoretical analysis of the mechanism and the evolution of the laser-induced plasma,the main factors affecting the intensity of the plasma spectra were analyzed,which is the theoretical basis of further study for the selection of experimental parameters and data analysis.In the instrument development,the structure of LIBS system and the method of selecting the components were introduced in detail.The optical path,data acquisition and control circuit of the high-resolution spectrometer were designed.And the wavelength was fine calibrated in the assistance of the spectral information of elements.Besides,a method to improve instrument flux based on deconvolution calculation and the method of discriminant classification based on PCA-LDA algorithm were discussed.The feasibility of these two methods was proved by related experiments.Finally,the self-made LIBS measuring instrument was tested and its resolution was proved to be 0.1 nm.The plasma spectra of coins,eggshells and soils were measured,which indicated the self-made LIBS measuring instrument could be applied to metal element analysis.