Increased identification rate of scrap metal using Laser Induced Breakdown Spectroscopy Echelle spectra

• The presented results show a new example where LIBS is proceeding more into the industrial application.
• Simultaneous single burst, online classification of 10 different kinds of untreated scrap metal.
• Sampling speed of 25 samples per second with average classification correctness varying between 76-100 %.
• Additionally possible pitfalls during development of chemometric models such as PCA and PLS-DA are being addressed.

In this paper we address the application of an Echelle spectrometer for metal sorting tasks using laser induced breakdown spectroscopy in the industrial environment. Echelle spectrometers guarantee the simultaneous detection of broad spectral intervals with sufficient spectral resolution, which is highly desirable for LIBS applications. Until today, this benefit was overshadowed by the reduced speed of detection which typically could not exceed 10 frames per second. In this paper we present a newly developed high speed classification setup for scrap metal sorting, equipped with an Echelle spectrometer, capable of classifying 25 samples per second using a single burst double pulse excitation, a fast EMCCD camera and an externally triggered, chopper based timing. Different multivariate discriminatory techniques (PCA, PLS-DA) are applied and compared to gain maximum use of the spectra created by this setup. A simultaneous discrimination of 10 classes was done with > 90% correctness for most classes and an analysis of possible sources of error unique for non-laboratory experiments is presented.