z-logo
open-access-imgOpen Access
Suppression of spallation induced nanoparticles by high repetition rate femtosecond laser pulses: realization of precise laser material processing with high throughput
Author(s) -
Shigemitsu Shin,
Jong Kab Park,
Doh-Hoon Kim
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.427168
Subject(s) - spallation , materials science , fluence , optics , laser , femtosecond , irradiation , ablation , laser ablation , optoelectronics , physics , engineering , quantum mechanics , neutron , nuclear physics , aerospace engineering
This paper reports a mechanism to suppress nanoparticle (NP) generation during femtosecond laser processing of 64FeNi alloy (Invar) to realize high precision fine metal masks. Nanoparticle redeposition during processing can reduce precision and ablation efficiency. Since Gaussian laser beams have spatially distributed fluence, NP types can vary even within a laser spot. Surface areas irradiated by the beam center with high peak fluence can be decomposed into vapor and liquid droplets by phase explosion; whereas positions irradiated by the beam edge, where fluence is close to ablation threshold, can be decomposed by stress confinement under the surface, known as spallation. Spallation characteristics were verified from target surfaces covered with exfoliation and fragments. It occurred above a certain number of pulses, indicating a significant incubation effect. Spallation induced NPs, i.e., agglomerated fragments, distort micro-hole size and shape, but were effectively suppressed by increasing repetition rate, due to increased surface temperature, i.e., heat accumulation. Suppression also occurred from direct sample heating using a hot plate. Thus, thermal energy can relax stress confinement and inhibit spallation induced NPs. Numerical simulation for heat accumulation also confirmed that suppression arises from thermal effects. Increasing repetition rate also helped to increase productivity.

The content you want is available to Zendy users.

Already have an account? Click here to sign in.
Having issues? You can contact us here