The depth of surface features plays a critical role in the functionality and performance of engineered surfaces. However, achieving high precision in volumetric laser ablation — particularly for deep features exceeding 100 µm — is challenging due to dynamic effects such as incubation-induced changes in ablation efficiency and altered laser-material coupling caused by the formation of Laser-Induced Periodic Surface Structures (LIPSS). These challenges are further amplified when processing complex geometries with varying target depths and heterogeneous surface conditions.

This work presents a fully industrial laser machining setup for depth-controlled volumetric ablation, integrating an ultrafast laser, galvanometer scanner, and online depth monitoring via coaxially aligned Optical Coherence Tomography (OCT). A custom-developed process control software regulates the ablation in real time and includes features to compensate for significant changes in surface topography, enhancing overall accuracy. The achieved depths were verified using Laser Scanning Microscopy (LSM).

The developed system enabled precise and reproducible fabrication of pockets in stainless steel with target depths ranging from 100 µm to 500 µm. Depth accuracy better than 2% was achieved across the different depths, alongside high surface quality with a roughness of 1 µm. The approach also allowed for automated processing of complex and multi-depth geometries, demonstrating its potential for high-precision laser ablation in industrial applications.