Stand-off analysis of moving targets using laser-induced breakdown spectroscopy

Abstract

This work investigates the capabilities of stand-off LIBS for the analysis of moving samples. The effects of sample speed, repetition rate and incidence angle of the laser beam on the sample have been studied. Stainless steel samples tilted from 0° to 45° at speeds up to 24 cm min⁻¹ have been analyzed at a distance of 10 m from the instrument. The spectral intensity of the spectra observed is related to the amount of sample surface overlapped by successive laser shots, and this can be controlled both by changing the laser repetition rate and the sample speed. As a proof of concept, a semi-quantitative analysis of stainless steel samples has been carried out under simulated field conditions—10 m from the laser source, incidence-collection angle of 40° and sample speed of 24 cm min⁻¹. Samples corresponding to five different stainless steel grades were sorted according to their content of Ni, Mo and Ti.