Periodic surface ripples in laser-treated aluminum and their use to determine absorbed power

Abstract

We report the first observation of surface ripples produced on a metal (pure and implanted A1) during pulsed laser treatment (Nd:glass laser in TEM00 mode, λ = 1.06 μm, 7 ns FWHM). Fringes with a characteristic spacing equal to the incident wavelength are readily seen near the periphery of laser spot, over a narrow region, resulting in an accurate delineation of melt threshold. Comparison with the calculated melt threshold leads to determination of the absorbed power. This method to evaluate the absorbed power can be applied to any material exhibiting surface ripples characteristic of melt threshold.