The route to microstructures with optical quality glass surfaces by fs laser ablation.

Glass substrates are highly valued for their transparency, stability and biocompatibility, making them essential in optics, photonics, chemistry and biomedical devices. Femtosecond lasers enable precise glass ablation due to the capability to deliver pulses with high energy density leading to nonlinear absorption. This study examined how parameters like pulse energy, scan line density and pulse repetition rate affect the surface roughness of 3D borosilicate glass structures. Analysis by means of AFM, µCT and SEM revealed parameter settings to minimize roughness and prevent substrate damage. Post-treatments like HF etching and annealing further enhanced surface quality, resulting in smooth, transparent (T = 85.35%) microstructures especially for novel optical and optofluidic applications.