Closed-loop laser micromachining based on in-situ depth monitoring

Conventional laser micromachining technologies rely on trial-and-error optimization to obtain precise surface geometry. In this study, we present a laser micromachining setup that enables the preparation of the desired surface geometry without the need for parameter exploration. The setup consists of a laser scanning system, a coaxial imaging system, a paraxial laser line projector, and a three-axis stage. The coaxial imaging system serves not only for positioning but also for in-situ depth monitoring via the laser triangulation method. After each processing, the ablation depth is measured to adjust the parameters for subsequent steps. Thus, feedback-corrected laser micromachining was achieved and can be used for rigorous applications.