1998 年 16 巻 4 号 p. 445-452
A YAG laser processing system in which the beams of three YAG lasers (two 2.0 kW continuous wave oscillators and one 1.5 kW pulsed oscillator) were combined on the input end of single optical fiber and transmitted through the optical fiber was developed. It was confirmed that the energy density distribution and the complex pulse shape control of the laser power were similar to those of one oscillator. The effect of three types of oscillation waveforms (continuous wave, rectangular modulated wave, rectangular modulated wave superimposed pulse wave) on penetration depth was examined by using this system. As a result, it was confirmed that the penetration depth with the rectangular modulated laser beam superimposed the pulse laser beam was deeper than that with the rectangular modulated laser beam and the continuous laser beam, though the average output powers of the three type laser beams were equal each other. The effective delay time of the pulse laser beam after rising of the rectangular modulated laser beam was two or three millisecond to obtain the deepest penetration. Moreover, the penetration depth increased with an increase in the pulse laser beam power to the total one. The deepest penetration depth with a rectangular modulated laser beam superimposed pulse laser beam became 1.7 times deeper than that with a continuous laser beam.