Assessing the limits of determinism and precision in ultrafast laser ablation

Abstract

Although ultrafast lasers provide unique capabilities for advanced manufacturing, important challenges remain since super-resolution naturally conflicts with high repeatability in material processing. In this work, we perform statistical analyses of ablation precision at varying pulse durations, down to the sub-picosecond regime. By comparing the results with a “noise model” accounting for laser fluctuations, we establish that pulses shorter than 200 fs allow us to obtain the highest achievable level of determinism. Our model is a simple extension of an extensively used method proposed by Liu in which error propagation theory is applied to allow us to derive and reach the limits of precision and reproducibility in laser machining. Its validity is confirmed by an experimental demonstration in which reproducible features as small as 1/10 of the beam size are produced with a stable laser source exhibiting energy fluctuations of 0.3%.