Optimizing the specific removal rate with the burst mode under varying conditions

The influence of pulse-bursts is investigated using different spot sizes and different wavelengths as well. The specific removal is calculated and compared as a function the peak fluence of the single pulses (not total fluence of the burst package). A drop in the specific removal for copper and alumi-num is observed for a 2 pulse-burst, whereas for a 3 pulse-burst the specific removal rate is larger than for the 2 pulse-burst and may exceed the rate observed in the single pulse mode in special cases. Possible explanations for these observations are given based on shielding effects and a pre-conditioning by previous pulses. The usage of pulse-bursts may also increase the process window and in addition influence the surface quality. The formation of small cavities on the machined sur-face often appearing in steel can be shifted to higher fluences if pulse-bursts are applied.