Studies On Theories And Experiments In Femtosecond Laser Ablation Of Metal

The technology of femtosecond laser machining can realize the non-thermal processing of almost any materials due to ultrashort time duration and ultrahigh peak fluence, the workspace is very small and the accuracy is very high, it has been widely used in micro-machining with different materials and has a good prospect in the application of micro-mold machining.The paper made research on femtosecond laser interaction with materials. Make the two-temperature model, describes interaction of ultrashort laser with solids, formatted simply, simulated the surface temperature of electron and lattice by finite-different method to understand the essence of non-thermal processing. Threshold model and phase explosion, the mechanism of femtosecond laser interact with metal, were investigated and proved by the ablation of single crystal copper in vacuum.In the foundation of theoretical analysis, ablation of tool steel (65Mn) with multiple Ti:Sapphire laser pulses of 50fs in air was investigated. The ablated diameter increased with increasing laser fluence and shot number, ablation threshold and incubation coefficient were measured by curve fitting. And the reason why laser-induced periodic surface structures grow was analyzed. Femtosecond laser micromaching of grovess was investigated in the paper. A logarithmic dependence of the groove depth on laser fluence was observed with two regimes characterized by different ablation rates and different thresholds, morphology and material property of different regimes were investigated. The groove depth was found to be inversely proportional to cutting speed and proportional to the number of passes. A depth limit was observed with reducing cutting speed or increasing passes. The cause of morohological features and influence of cutting parameter was investigated.The paper investigate the rule of femtosecond laser interact on steel and the relation between machining parameters and results. The relust has a long meaning of machining micro parts and developing complex mold for the future .