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为了提高纳秒短脉冲激光微孔制备的加工效率,采用了一种新颖的双脉冲方法。通过时域脉冲塑形将调 Q激光器产生的普通纳秒脉冲变换为具有几十纳秒脉冲时间间隔的双脉冲序列。使用这种双脉冲序列对不锈钢试件进行打孔实验,与传统单脉冲打孔结果对比发现,在一定条件下双脉冲序列能将打孔烧蚀率提高一个数量级以上。实验中研究了脉冲能量、重复频率以及环境气体压力对双脉冲序列烧蚀率的影响,并将脉冲烧蚀率提高的原因归结为材料预加热、材料溶液的加速以及瞬时准真空环境,对各种机制分别进行了讨论。结果表明,采用双脉冲方法替代普通单脉冲进行金属打孔,可以在相同能量密度,相同脉冲重复频率的情况下大幅度提高脉冲烧蚀率,为高效激光微孔制备提供了新方法。
In order to improve the processing efficiency of nanosecond short pulse laser micropore preparation, a novel double pulse method is adopted. The normal nanosecond pulses generated by Q-switched lasers are transformed into double-pulse sequences with tens of nanosecond pulse intervals by time-domain pulse shaping. Compared with the traditional single-pulse drilling results, this double-pulse sequence was used to drill the stainless steel specimens. It was found that the double-pulse sequence can increase the perforation ablation rate by more than one order of magnitude under certain conditions. The influence of pulse energy, repetition frequency and ambient gas pressure on the ablation rate of double pulse sequence was studied in the experiment. The reason of the pulse ablation rate was attributed to the material preheating, the acceleration of material solution and the instantaneous quasi-vacuum environment, The mechanisms were discussed separately. The results show that the double pulse method can replace the ordinary single pulse for metal drilling, which can greatly improve the pulse ablation rate with the same energy density and same pulse repetition frequency, which provides a new method for high efficiency laser micropore preparation.