Role of lens to sample distance during laser-induced damage in zinc targets

Abstract

We report on the experimental investigation of nanosecond laser-induced Zn target damages versus the lens to sample distance (LTSD). The varieties of typical surface profiles associated with the evolutions of laser ignited plasma expansion were described in detail. According to the observed results, an established transient state of modified structure within an early phase of single-pulse laser ablation should play a critical role in the steps of final damage and plasma expanding. Due to the transient state, re-enhance absorption of laser energy will occur immediately in this case. On the other hand, it is deduced that the rise curves of transient absorption coefficient should obey an exponential growth, as the LTSD increasing from 103 mm to focal length ~111 mm. © 2012 by Astro, Ltd.