Interaction Of Femtosecond Laser Pulses With Metal Materials

In this thesis, theoretical and experimental studies on Interaction of femtosecond laser pulses with metal materials are presented. The main contents are classified as follows:1. The ablation processing of metal materials with femtosecond laser pulses were simulated by the 2D Two-Temperature Model(TTM), the electronic and lattice coupling time which was calculated is picosecond magnitude; According to the characteristic of femtosecond laser ablation, a definition on heat affected zone of femtosecond laser ablation was proposed, and on the basis of the definition, heat affected zone of femtosecond laser ablation was calculated, it is nanometer magnitude; besides, the cooling rate of lattice, the ablation rate of single pulse and accumulation behavior of multiple pulses were calculated. Besides, the effects of material parameters on them were studied.2. The experiments on femtosecond laser micromachining of metal plate were studied.(a). The multiple pulses ablation on the surface of Al alloy plate: The experiments perform in different energy and different pulse numbers. In the same laser power, the more pulses there are, the bigger the ablation radius is and the smaller the threshold is. The multiple pluses threshold,single pulse threshold and incubation coefficient are calculated from the experiment results.(b). The metal drilling: In order to get optimal technology of metal drilling, different N.A. of objective, laser power, scanning speed were chosen. It is showed that the helical drilling is a better drilling way, Because it leads to regular circular and repeatable holes. And analyze the effect of gas medium on the micromachining results.