Film-free laser printing: Jetting dynamics analyzed through time-resolved imaging

While the technique proves feasible for microprinting, a deeper understanding of the influence on the printing process of its most relevant technological parameters is required. Therefore, in this work we analyze through time-resolved imaging the laser pulse energy influence on the bubble-jet dynamics of a film-free liquid ejection event. We simultaneously image the evolution of both cavitation bubble and ejected liquid, showing that for all the analyzed energies the transfer mechanism is mediated by the formation of two liquid jets which originate during the successive expansion-collapse cycles that the cavitation bubble undertakes close to the liquid free-surface. We find that the evolution of both bubble and jets depends strongly on the energy. The different bubble geometries that appear are interpreted in terms of the counter-jet interaction with the bubble, which in its turn depends on the energy.