Acoustic signal monitoring in laser paint cleaning

Laser paint removal has many advantages compared to traditional paint removal methods and has been widely used in the industry. A closed-loop control based on real-time monitoring of the laser paint removal process is essential to achieve a good clean effect without damaging the substrate. The acoustic signals generated in various stages have been studied experimentally. The results show that the property of the acoustic signal is closely correlated with the status of laser paint removal. The amplitude and the local standard deviation of the acoustic signal in the frequency range of 7–10 kHz gradually decreases to a steady value with the removal of the paint. The change of these two factors can reflect the status of laser paint removal more realistically than the signal amplitude in the time domain. Compared with the laser induced breakdown spectroscopy method, we found that monitoring based on acoustic signal works on a wider laser fluence range. We proved that this method can be used to evaluate whether the paint is cleaned or not when laser works in a scanning model. Our work can benefit the real-time monitoring and close-loop control of laser paint removal. (paper)