Integration of three high power Nd–YAG lasers to one beam and its application in stainless steel welding

Abstract

An Nd–YAG laser processing system has been developed in which the beams of three Nd–YAG lasers (two 2·0 kW continuous wave oscillators and one 1·5 kW pulsed oscillator) were combined at the input end of a single optical fibre and transmitted through the optical fibre. The power distribution of the integrated beam, even at the defocused point of the processing optics, was not split between the three beams. Complex pulse waveform control was therefore possible. The effect of the waveforms on penetration depth was examined. Penetration depth for the rectangular modulated laser beam superimposed on the pulse laser beam with a delay was deeper than that for the rectangular modulated laser beam and the continuous laser beam, even under the same average power condition. The effective delay was 1–3 ms. Deepest penetration depth for the rectangular modulated laser beam superimposed on the pulse laser beam was 1·7 times that for the continuous laser beam.