CO2 laser-produced ripple patterns on Ni<i>x</i>P1−<i>x</i> surfaces

Abstract

When CO2-laser pulses of ∼50 ns duration and intensity of ∼100–500 MW/cm2 are incident upon NixP1−x surfaces in oxygen-containing atmospheres, distinctive ’’ripple’’ patterns are etched into the surfaces. The ripple wave fronts are normal to the E field and vary in spacing from ∼λlaser at normal incidence to ∼0.5λlaser for π polarization at grazing incidence.