Novel solid-state picosecond lasers provide a strong benefit for high precision micro-machining. Pulse repetition rates as high as > 500 kHz with pulse energies of > 4 µJ enable fast machining with the precision of low fluence ablation. In addition, new potentials for these lasers are given by advanced modulators with digital timing control that allow the user to generate sequences or groups of pulses: E.g. a sequence of two pulses can be generated and repeated up to 300 kHz. The amplitude of these two pulses can be adjusted independently and the delay is selectable in 20 ns steps. This kind of pulse-strategies with picosecond lasers can support higher ablation rates, similar to the machining results that were demonstrated with double ns-pulses, recently. In another application, groups of > 20 pulses were repeated with > 50 kHz for ultra-precise machining. The distribution of the energy yields a few hundred nJ per pulse and results in an ablation depth per pulse in the range of several nm. Therefore the ablation depth formed by a group can be digitally controlled by the number of pulses in group. Samples for high quality drilling, cutting and structuring of several materials will be presented and the new potentials of this kind of picosecond laser processing with improved precision and speed will be discussed.
Highest quality in laser micromachining is obtained using ultrashort light pulses with energies slightly above ablation threshold. Together with very high pulse repetition rates and a new type of fast beam deflection technology, new pathways in laser micromachining have been opened. As examples, we show results of improved surface texturing and carbon-fiber reinforced plastic material removal using this technology.
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