Direct correlation of local fluence to single-pulse ultrashort laser ablated morphology

Basic studies on ultrafast laser ablation processes are important for expanding their utility. In particular, understanding the ablated morphology in relation to the incident pulse is critical for micromachining, and an important benchmark for simulations. However, current morphological analyses rely on vast simplifications of experimental conditions, such as a singular fluence value to reduce a unique beam profile, or the maximum crater depth or diameter to describe the ablated morphology. Here, we develop a morphology analysis method in which we take the full two-dimensional information of both the input beam profile and the ablated morphology, and spatially correlate the two without data reduction. We show, using sapphire as a benchmark material, that this serves as a robust way to extract well-studied values and dependencies, such as the ablation threshold, and also as a way to probe the spatial independence of the process. We anticipate that our findings will modernize current study techniques to meet the demand for increased, high-quality data such as that required for artificial intelligence-based analysis. Describing the laser ablation process with reduction-free data is important for furthering its use in modern manufacturing. Here, fluence maps, correlating laser beam intensity and ablated depth at each point in a full two-dimensional space, provide a method to probe ablation morphology in cases of arbitrary beam and crater profiles.

Automated summary

This study develops a new method for analyzing laser ablation morphology without reducing data, spatially correlating the input beam profile and ablated morphology. It is beneficial for extracting well-studied values and dependencies, as well as probing the spatial independence of the process.