Back Deposition of Ablated Particles onto Sample in Femtosecond Laser Processing of Metals

A comparative study of the redeposition of ablated material back onto a metal sample irradiated with femtosecond laser pulses in 1-atm air and vacuum shows that the amount of material redeposited around the ablated area is significantly greater in air than in vacuum, it is speculated that due to direct air breakdown a high-pressure of the ambient gas plasma -applied to the sample surface after the femtosecond laser pulse restrains the expansion of the ablated material and thereby enhances the redeposition of the ablated material