  The fragmentation of a liquid metal droplet induced by a nanosecond laser
pulse has been studied well. However, the fragmentation mechanism may be
different, when a subpicosecond laser pulse is applied. To discover the details
of the fragmentation process, we perform a hydrodynamic simulation of a liquid
tin droplet irradiated by a femtosecond laser pulse. We have found that the
pressure pulse induced by an instantaneous temperature growth in the skin layer
propagates from the one side of the surface of a spherical droplet and focuses
in its center; at the release a big cavity is formed at the center of a
droplet; the pressure wave release at the backside surface may cause the
spallation.
