Investigation of the reflection of CO2 laser radiation from targets in air

An experimental study was made of the reflection of high-power pulsed CO2 laser radiation from targets of graphite and polished aluminum in air. It was found that for a flux density in the range 2×106 – 4×108W/cm2 the radiation was reflected both from the target surface and from a plasma formed close to it. The conditions and the formation time of a plasma layer screening the target were determined. The directional polar diagram of the radiation reflected by the plasma was studied and the reflection was found to be strongly nonspecular. The total laser energy losses on reflection were measured; they reached 43% for the graphite and more than 50% for the aluminum.