Study of the fluence dependent interplay between laser induced material removal mechanisms in metals: Vaporization, melt displacement and melt ejection

Three quantitative methods, namely profilometry, high speed imaging and recoil momentum measurements using a ballistic pendulum, are used to determine the interplay of vaporization, melt displacement and melt ejection on nanosecond laser induced material removal. At low to moderate fluences (<7 J cm−2) material removal occurs via vaporization and melt displacement in aluminium. At high fluences (>7 J cm−2), material removal occurs predominantly via the explosive ejection of liquid droplets from the melt pool.