Double-pulse irradiation using a near-IR femtosecond laser (lambda = 775 nm) was used to study the mechanism of the laser-induced plasma-assisted ablation (LIPAA) process. The dependence of the ablation depth on the delay time between the first and the second pulse for various target-to-substrate distances was investigated. The first pulse generates the laser-induced plasma from the metal target, but does not induce ablation of the glass substrate. The second pulse induces the high-efficiency ablation of the substrate, delayed by several nanoseconds (ns). A possible mechanism of the conventional LIPAA process using a ns pulsed laser is discussed based on the obtained results. (c) 2005 Elsevier B.V. All fights reserved.