System and method for quantitative analysis of the elemental composition of a material by laser-induced breakdown spectroscopy (LIBS)

A system for quantitative analysis of the elemental composition of a material from a sample containing a plurality of elements by laser-induced breakdown spectroscopy, each element having several constituents, the system comprising:

• a laser radiation source that can heat the material so as to generate plasma emitting radiation;
• optical means configured to direct and focus the radiation from the laser source to the sample;
• an optical system configured to receive the radiation emitted by the plasma generated by the sample;
• a system for spectroscopic analysis of optical signals by measuring the emitted radiation to obtain a spectrum;
• a computing device comprising:
• means for identifying, from the obtained spectrum, the spectral lines of interest among spectral lines emitted by the constituents of each element of the sample,
• means for measuring intensities of the spectral lines of interest,
• means for estimating a temperature of the plasma,
• means for estimating an electron density of the plasma,
• means for estimating a dimension of the plasma along the direction of observation,
• means for calculating the chemical composition of the plasma from the temperature and the electron density values and values relating to the elemental concentrations of each element of the sample,
• means for calculating the absorption coefficient of the plasma according to the wavelength in spectral zones selected for observing the spectral lines of interest,
• means for calculating a spectral radiance of the plasma,
• means for calculating a spectrum from the calculated chemical composition, the calculated absorption coefficient, and the calculated spectral radiance of the plasma,
• means for comparing the intensity and the shape of the calculated spectrum with the intensity and the shape of the measured spectrum,
• the means for calculating the chemical composition of the plasma, the means for calculating the absorption coefficient, the means for calculating the spectral radiance, and the means for comparing are configured so as to execute calculations and comparisons successively and iteratively, wherein the values of the temperature of the plasma, the electron density of the plasma, the dimension of the plasma, and elemental concentrations being adjusted at each iteration until a difference is obtained between the intensity and the shape of the calculated spectrum and the intensity and shape of the measured spectrum that is less than or equal to, by absolute value, a predetermined threshold value, and
• means for dividing the plasma into an increasing number of zones, the division means being configured to execute the division when the difference obtained between the intensity and the shape of the calculated spectrum and the intensity and the shape of the measured spectrum is a minimum, the minimum being greater, by absolute value, than the predetermined threshold value.