Method for preparing millimeter-class deep hole through femtosecond lasers

The invention relates to the technical field of laser hole forming, in particular to a method for preparing a millimeter-class deep hole through femtosecond lasers. The method includes the steps that a lens is used for focusing the femtosecond lasers into a filament, and the femtosecond lasers form a relatively-stable light filament channel in air; the average power of the femtosecond lasers is adjusted, and the length of the light filament channel is changed; a target material is put at different positions of the light filament channel under the same condition, the point with the highest ablation strength in the light filament channel is found out, then the target material is fixed to the point with the highest ablation strength to be machined, and therefore the millimeter-class deep micro hole is obtained; a scanning electron microscope is used for observing the diameter and the surface appearance of the deep micro hole; and deep micro holes different in parameter are obtained by changing the average power and the machining time of the femtosecond lasers. Due to the fact that the femtosecond lasers can form the light filament channel which has very high strength and is good in uniformity, long in spreading distance and relatively stable in air, the requirement for an experimental platform is also relatively low, and the cost for preparing the deep micro holes is greatly lowered.