Acoustic detection of laser-induced plasma emission by means of a fiber-Bragg grating sensor

Abstract

Laser-induced breakdown spectroscopy (LIBS) is an analytical tool able to estimate the atomic composition of materials, without sample preparation and in a short time. One drawback of this technique is that the quantitative analysis is not as precise as other established methods, in part because of the pulse-to-pulse fluctuations of the energy delivered to the sample. These fluctuations can be compensated by monitoring the acoustic wave emitted by the plasma, which is related to the ablated mass. In this paper, we propose the use of a fiber-Bragg grating sensor to detect and measure the acoustic shockwave. A processing scheme is proposed to derive the acoustic energy from the sensor waveform. The experiments show that there is a correlation between the sensor’s response and the laser pulse energy, so it can be used as a monitoring signal of the ablation process.