Wavelength optimization for machining metals with the harmonic generationsof a short pulsed Nd : YAG laser

The wavelength conversion for a short pulsed Nd:YAG laser has been implemen ted from infrared to visible and to ultraviolet spectra by using nonlinear optical crystals. The analytical method of wavelength optimization for mach ining metals with various harmonic generations of a Nd:YAG laser is present ed in this paper. Combining the absorptivity of metal and the conversion ef ficiency of laser apparatus, the absorption efficiency is proposed to selec t an optimum machining wavelength. Various metals have different optimum ma chining wavelengths. The optimum machining wavelengths for gold, silver, an d copper are in the third-, fourth- and second-harmonic generations of a Nd :YAG laser, respectively. For other metals, such as nickel, their optimum m achining wavelengths are all in the fundamental wavelength of a Nd:YAG lase r. (C) 2000 Elsevier Science Inc. All rights reserved.