Novel LIBS–Raman Hybrid System for Borehole Logging

The first dedicated hybrid laser-induced breakdown spectroscopy (LIBS)–Raman system for borehole logging in mineral exploration was developed from scratch and successfully tested in real operative conditions. It represents an innovative approach to the compositional mapping of drill holes based on the mentioned photonic techniques, many spectroscopic atomic and molecular measurements, and associated chemometric elaborations. This can allow collecting thorough compositional information on the mineral formations intersected by a drill hole and on the evaluation of the corresponding mineral deposits. The novel analytical system was designed using very compact photonic and electromechanical components and adopting effective solutions that allowed housing the measurement head, spectrometers, Raman excitation laser source, and data communication components within a 2” diameter cylindrical stainless-steel tube. Qualitative optimization tests were carried out in different operative conditions, while an example calibration for quantitative LIBS analyses was performed in order to address the specific case of magnesite mineral exploration. The results achieved demonstrate the viability of the present approach in mineral exploration. Furthermore, they also show that the optical scheme here adopted for confocal LIBS and Raman spectroscopy can be adapted to design measurement heads suitable for a variety of analytical configurations dedicated to the solution of material characterization problems in various fields of application.