Effect of sample temperature and laser ablation angle on optical emission and acoustic signals from laser-induced zirconium plasma

A fiber-coupled, acoustic-wave-assisted (AW) microchip laser-induced breakdown spectroscopy (mLIBS) system was developed to analyze the elemental composition and surface imaging. In this study, we measured the dependence of sample temperature and laser ablation angle (LAA) on the laser-induced plasma-optical emission (LIP-OE) and LIP-acoustic signal (LIP-AS). The intensity of the LIP-OE and ablated mass at three different temperatures and eight different LAAs were estimated using a zirconium sample. Simultaneously, we investigated the LIP-AS amplitude, propagation speed, and shape by synchronizing the AW-mLIBS system with a high-speed camera. The results revealed that the LIP-OE increases with increasing temperature and is unaffected by LAA up to 40 degrees because the amount of the ablated mass was similar to the plasma. Additionally, no considerable variation in plasma temperature was obtained using the Boltzmann method over the sample temperature. However, the propagation speed of the LIP-AS differs with temperature but has marginal angular dependence because the LIP-AS propagates as semispherical. Furthermore, no considerable changes were observed in the LIP-AS amplitude up to 100 degrees C, and the LAA showed a similar tendency to that of the LIP-OE.