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K: Kurzzeitphysik

K 5: Laser material processing

K 5.2: Vortrag

Donnerstag, 5. April 2001, 17:50–18:05, EB107

Hole formation and drilling progress analysis during high-aspect ratio drilling using ultra-short pulsed solid-state lasers — •D. Breitling¹, T.V. Kononenko², S.M. Klimentov², P. Berger¹, V.I. Konov², and F. Dausinger¹ — ¹Institut für Strahlwerkzeuge (IFSW), Pfaffenwaldring 43, D-70569 Stuttgart — ²General Physics Institute, Vavilov St. 38, 117942 Moscow, Russia

The dependence of the ablation rate on pulse duration and pulse energy has been the subject of numerous studies in the past. Being restricted, in general, to surface ablation those investigations are of limited value for understanding a process of high technological interest, the drilling of high-aspect ratio holes, where the minimum energy density required for full penetration was found to depend significantly and nonlinearly on the material thickness. Apparently, energy coupling, loss mechanisms and material removal vary strongly with the geometry of the interaction zone which changes considerably during the process of penetration. Thus, the drilling progress in transparent CVD-diamond and PMMA was visualized in-situ by high-speed video microscopy for pulse durations in the ps- and sub-ps regimes. Simultaneously, the influence of laser-ignited plasma absorption was studied by transmission measurements. Based on the experimental results the contribution will present a proposal for the basic understanding of the hole formation process.