Change of reflectivity of metallic surfaces during irradiation by CO2-TEA laser pulses

Measurements of the decrease in reflectivity of metallic surfaces as a function of time during irradiation by pulses from a CO2- TEA laser are described. The TEA laser delivered power densities up to3 × 10⁸W/cm2in a 100-ns-duration pulse. The reflectivity was monitored as a function of time by a probing beam from a low-power continuous CO2laser operating at 9.6 μm, and focused onto the same area struck by the TEA laser pulse. This paper presents data on the decrease in specular reflectivity as a function of time under various conditions of laser power density, laser pulse duration, ambient air pressure, and cumulative number of pulses on the same area.