Microdrilling of metals with ultrashort laser pulses

The pulse duration requirements for melting-free and burr-free drilling of metals have been observed in detail. It will be shown that the highest proc ess efficiency and hole quality can be achieved by using pulse durations in the subpicosecond time scale. Furthermore, it will be demonstrated that no nlinear distortions due to high intensities can be successfully minimized b y applying diffractive optical elements for beam forming. The influence of the polarization of the laser radiation on the process quality will be disc ussed. Experimental results will show that the rotation of linear polarized radiation during percussion drilling significantly improves the quality of the hole geometry. (C) 2000 Laser Institute of America. [S1042-346X(00)005 01-5].