Polarization effects on ablation efficiency and microstructure symmetricity in femtosecond laser processing of materials-developing a pattern generation model for laser scanning

This paper investigated the effects of femtosecond laser beam polarization on ablation efficiency and microstructure symmetricity for 64FeNi alloy (Invar) sheet processing to fabricate fine metal masks. Itwas found that the ablation efficiency for linear polarizationwas approximately 15% higher than that for circular polarization due to electric field enhancement induced by low-spatial-frequency laser-induced periodic surface structures (LIPSS). The hole size and sidewall taper angles for the microstructures generated by linear polarization were asymmetric, whereas those generated by circular polarization were symmetric due to non-oriented LIPSS. The asymmetric and symmetric three-dimensional microstructure profiles, measured by using a confocal laser scanning microscope, were verified by employing an analytical model that was derived using the total input fluence and the ablation rates for linear and circular polarizations, respectively. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This study investigated the effects of femtosecond laser beam polarization on the efficiency and symmetry of metal sheet processing. It was found that linear polarization resulted in higher ablation efficiency but asymmetric microstructures, while circular polarization led to lower ablation efficiency but symmetric microstructures. Experimental results verified the asymmetric and symmetric microstructure profiles.