DRILLING WITH FIBER LASERS

摘要

For drilling holes such as cooling holes in tool formsrnor turbine blades with diameters from 100 μm up torn1.5 mm flash lamp pumped laser sources e.g. slabrnlasers are commonly used. These laser sources havernpeak powers of several kW at pulse durations fromrnmicroseconds up to milliseconds with a high beamrnquality. Due to the beam quality, small spot sizes andrnintensities greater than 10~6 W/cm~2 are achieved. Thernmean power of these laser sources is in the range ofrnsome mW up to several hundred W rather small.rnSo far fiber lasers are not used for laser drilling due tornsmall peak powers and intensities. Meanwhile, fiberrnlasers with a scalable output power of 1 W up to 50rnkW in multimode or up to 10 kW in single-mode withrna beam quality of M~2 < 6 in the multimode andrnM~2 < 1.1 in single-mode are offered in cw.rnFurthermore fiber lasers with a beam quality of M~2 < 6rnare offered with a maximum peak power of 6 kW in arnpulsed operation mode. With these fiber lasers drillingrnseems to be possible. Thus laser drilling with fiberrnlasers is investigated and compared to flash lamprnpumped Nd:YAG lasers.