Laser ablation impulse dependence on beam Spatial-Profile

Abstract

In many previous studies, laser ablation impulse was evaluated using fluence, which is obtained by dividing the beam energy by the beam projection area on the target. This method does not consider the difference in the spatial profile of the beam energy. However, in certain applications, the effect of the profile should be evaluated for a more precise estimation of the impulse. In this study, the dependence of the ablation impulse of a nanosecond pulse laser on the beam profile was investigated. Pure aluminum, extra-super duralumin, and oxygen-free copper were used as the ablation target materials. The ablation impulse, laser energy, and beam profile were simultaneously observed. A dependence of the impulse on the beam profile was observed for all the target materials. A novel equation containing two tuning parameters that connect the profile and impulse was derived using a simple physical model. By fitting these parameters, the parameters with which the impulse could be predicted from the beam profile with sub-μN·s precision was obtained for all the target materials. This work not only establishes a method for predicting the ablation impulse from a given profile, but also proposes parameters that are independent of the profile’s effect. These parameters can be used to quantitatively evaluate impulse generation.