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 aluminum 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 preconditioning 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 surface often appearing in steel can be shifted to higher fluences if pulse-bursts are applied. Keywords: burst mode, pulse-burst, ps-pulses, specific removal rate, energy efficiency