Femtosecond material processing is a predominantly non-thermal form of material ablation.  This characteristic means that the results of ablating a material using a femtosecond pulse are highly deterministic and repeatable, meaning that that the machined features are well-suited to being controlled and optimised using a feedback system.

Unlike previous work combining adaptive optics and laser machining we use the machining outcome itself as the fitness parameter for an optimisation procedure (shown below as flow diagram).

The box shows the ablation profiles for elliptical and circular targets. The main image shows the convergence towards the target as the simulated annealing algorithm proceeded. The columns (left to right) show the starting condition, intermediate result and final annealed hole