A new technique for increasing the laser penetration efficiency of metals has been developed. By amplitude modulating a freehyphen;running neodymium:yttrium aluminum garnet laser pulse, the depth of the crater was increased and the threshold energy for reliable hole drilling was decreased significantly. It was observed that the effect of chopping was optimal at 8ndash;12 kHz with a 70percnt; duty cycle. We believe that this improvement is due to an increase in the vapor recoil pressure and reduced plasma screening. Possible acoustic resonance effects have also been considered and will be discussed.
展开▼
