In-situ Monitoring of the Interface Status and Ablation Depth in Ultrafast Laser Drilling

Ultrafast laser processing is particularly well-suited for the processing of heterogeneous materials due to its advantages such as a wide range of materials applicability and high machining quality.However, the ablation depth has been difficult to control via the axial feed.In this situation, excessive damage and non-uniform ablation will occur in laser processing.In-situ monitoring and control of the machining process is one of the most promising methods to solve the problems.In this paper, we report an innovative method for in-situ monitoring of the interface status and ablation depth in ultrafast laser drilling of heterogeneous materials using optical coherence tomography (OCT).Firstly, the signal analysis and processing of the interference signal are developed for extracting the depth information.And then the interface detection of the heterogeneous materials and the measurement of the corresponding thickness before the drilling are demonstrated.Finally, the in-situ monitoring of the ablation depth is achieved.This study demonstrates the feasibility of utilizing spectral-domain optical coherence tomography (SD-OCT) for interface detection and in-situ monitoring of ablation depth in ultrafast laser drilling.The findings underscore the potential of SD-OCT in optimizing and achieving precise control of manufacturing processes.