Development and Validation of a Calculation Routine for the Precise Determination of Pulse Overlap and Accumulated Fluence in Pulsed Laser Surface Treatment

Abstract

In laser material processing, a variety of parameters like pulse fluence, total dose, step size, and pulse-to-pulse overlap are used to define and compare laser processes. Of these parameters, the pulse-to-pulse overlap can be the hardest to access as it is not implemented directly but instead depends on the spot diameter, its shape, and the respective scanning path that is used to cover the surface. This article shows that existing calculation routes overestimate the actual overlap by up to 21%. A novel calculation route is developed that greatly facilitates the determination of the pulse overlap and thereby the average number of laser pulses that interact with a given point on the surface. This approach makes it possible to achieve more reliable and comparable laser processes, which in return leads to better control of the procedure as the effect of individual parameters on a given output can be determined with greater precision.