Acoustic Trilateration Monitoring for Laser Surface Processing

As the laser processing industry grows bigger every year, the need for process monitoring grows with it.To this extent, in this paper, we will present a new and innovative way to monitor the spatial accuracy of laser processing based on acoustic monitoring and multilateration of the soundwave emitted during the laser-material interaction.During laser surface processing, the interaction of the laser with the material's surface emits a soundwave.By placing an array of various acoustic sensors surrounding the processing area, one can measure the difference in Time-of-Flight of the shockwave that is emitted by the laser ablation.Once this time difference is measured, it becomes possible to locate the origin of the sound with sub-millimeter accuracy.The marking of a QR code by a ns pulsed laser will be used to showcase the viability of this method.The real location of the surface marking process will be compared with the location obtained in-line with the acoustic trilateration monitoring.After demonstrating this new method, we will discuss its potential applications for the laser processing industry, the limitations it suffers, and how those issues could be mitigated or overcome.