Imaging laser-induced plasma under different laser irradiances

The ablation process of a sample in Laser-Induced Breakdown Spectroscopy (LIBS) is fast and dynamic. Investigating such dynamic process requires a good temporal and spatial resolution in order to understand the physical processes involved. However, the LIBS instrumentation tends to be versatile and price sensitive. For this reason, the goal of this work is to design a basic optomechanic construction satisfying the needs of plasma imaging experiment and providing the necessary performance at the same time. The optomechanic module is simplified and consists of an objective and a gated low-cost CMOS detector. For each experiment, multiple images of the plasma were collected and averaged to achieve a better accuracy. The expansion of plasma is imaged with 0.2 mu s temporal resolution where Laser Supported Combustion (LSC) and Laser Supported Detonation (LSD) expansion is observed. The size of plasma is compared with the emitted radiation of analytes of interest. Such data are used for an improvement of the signal stability. We created acalibration model for nickel, where we observed an improvement in coefficient of determination; rising from 0.914 using no standardization to 0.962 with a standardization to the plasma size.