Resonant response of the keyhole with beam modulation Available to Purchase

The presence of vibrational eigenmodes of the keyhole can be inferred during laser welding through the appearance of characteristic emission frequencies in acoustic and optical spectra. Such modes would involve specific resonances in the motion of the liquid surrounding the keyhole, but cannot be observed by direct observation in metals. Similar resonances should be present in other materials, and would be expected to be enhanced by beam modulation at the resonance frequency. We report on the generation of such stable resonances in the “drilling” of liquid glycerol using modulated CO₂ laser radiation and show how vibrational eigenmodes may be stabilized by beam modulation at certain frequencies. Keyhole morphology under these conditions can be directly related to specific components in acoustic spectra.