LIBS-acoustic mid-level fusion scheme for mineral differentiation in terrestrial and Martian atmospheric conditions

C. Alvarez, P. Purohit, J. Moros, J.J. Laserna, Analytical Chemistry, 2022, 94, 1840 – 1849


The concomitant shockwave produced alongside the plasma during a laser-induced breakdown spectroscopy event can be recorded to obtain information related to the physical traits of the inspected sample. In the present work, a mid-level fusion approach is developed using simultaneously recorded LIBS and acoustic data to enhance the discrimination capabilities of different iron-based and  calcium-based mineral phases which exhibit nearly identical spectral features. In order to do so, the mid-level data fusion approach is applied by associating  principal component analysis scores of LIBS intra position signal variability with the acoustic wave peak-to-peak amplitude and the slope of the acoustic signal span. The discrimination hit rate of the mineral phases is obtained using linear discriminant analysis. Owing to the increasing interest  for in-situ applications of LIBS+acoustics  information, samples are inspected in a remote experimental configuration and under two different atmospheric  conditions, Earth and Mars-like conditions, to validate the approach. Particularities conditioning the response of both strategies under each atmosphere are discussed to provide insight to better exploit the complex phenomena resulting in the collected signals. Results reported herein demonstrate for the first time that the characteristic sample input in the laser-produced  acoustic wave can be used for the creation of a statistical descriptor to synergistically improve the capabilities of LIBS of differentiation of rocks…


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