The Study Of Femtosecond Laser Micromachining

In this dissertation, part of theoretical and experimental studies on the applicationof femtosecond laser in micro-nanomachining field are presented.The main contentsin this dissertation are classified as follows.1.The ablation processing of copper foil with ultrashort laser pulses was simulated bythe Double-Temperature Equation(DTE), which was formatted simply. The ablationrate of the copper was attained on the basis of the simulation of the electronic andlattice's temperature. The simulation results show that the greater the laser fluence is,the longer the duration of ablation lasts and more material is removed. Theexperimental results are accorded with the theoretical analysis.2.In our investigations on machining techincs at high laser fluence, a commercialfemtosecond laser workstation is used. Several methods are adopted to improve thequality of machining, and at the same time some researches are carried out as belows.(a). Drilling experimental reserches: the drilled holes have very good cylindricalgeometry and high quality.(b). Cutting experimental reserches: with micro-nano size,high speed,great quality,cutting copper foil experiments are finished.(c). Masking: In order to improve the efficiency of machining, the beam offemtosecond laser is modulated by mask.3 . Reserch on ablation with femtosecond laser on the surface of organicmaterial(PMMA) has proceeded. The relationship between the characters offemtosecond laser, the speed of 3-D stage and the width of line is obtained bycalculation. The ablation experiment is accomplished. Comparing the experimentresult with the calculation, we could get some conclusions, which are valuable forselecting right characters of laser and speed of stage to get satisfying width of line andcontinuity. In the experiment, the femtosecond laser pulses are directly generated bythe Ti:sapphire oscillator. Some kinds of microstructure gratings on the surface ofPMMA are scored. Different diffraction patterns are presented as results of differentsize and array of gratings.