Discrimination of bimetallic alloy targets using femtosecond filament-induced breakdown spectroscopy in standoff mode

The femtosecond filament-induced breakdown spectroscopy (FIBS) technique coupled with principal component analysis (PCA) is demonstrated for standoff (ST) analysis of metals, alloys (Al, Cu, brass, stainless steel), and bimetallic strips (Ag@Cu, Ag@Au with varying weight percentages). The experiments were performed by analyzing the filament-produced plasma at similar to 6.5 m from the laser. The plasma emissions were collected using a Schmidt- Cassegrain telescope (6 '' f/10) at similar to 8 m away. The variations in intensities of persistent atomic transitions in the FIBS spectra clearly reflected the varying weight percentage in bimetallic strips. Furthermore, PCA was successfully utilized to discriminate the metals, alloys, and bimetallic strips batch wise and altogether. Our results demonstrate the capability of femtosecond ST-FIBS for ST analytical applications. (C) 2018 Optical Society of America