Pulse laser ablation experiments at semiconductor-grade silicon (111) and SAE 304 stainless steel were performed with femto- and nanosecond pulse durations. Threshold fluences in dependence of beam radius (1.6-100 mu m) and density of low -density defects (LDDs) have been determined for both materials and pulse durations. The experimental findings are supported by a recent quantitative model describing the strong dependence of the modification/ablation/damage threshold fluence on beam radius and pulse number. The importance of LDDs in the ablation mechanism has been confirmed. (C) 2016 Elsevier B.V. All rights reserved.