Study on the applicability of LIBS to sorting

LIBS (Laser Induce Breakdown Spectroscopy) could be considered one of the best sensing methods to apply to metal sorting process because this method can detect most of the elements with high accuracy. However, the method still has many problems to be solved for the application. In this paper, we investigated the effects of basic parameters, such as laser pulse energy, focal position, plasma detection delay time, etc. on the LIBS performance. From the above investigation it has been found that spectra intensity and P/B (Peak/Background) ratio was increased with increasing laser pulse energy and that the intensity and P/B ratio were rapidly decreased when laser focal position is off the sample surface by over approx. 2 mm. We also found out that the spectra intensity was gradually decreased with increasing plasma detection delay time but P/B ratio showed the maximum at around 8 μs and that the delay time to obtain the maximum P/B ratio was increased with increasing laser pulse energy.