Product Code: PIC2008_808

The Absorptance of Metal Surfaces to Nd:YAG/Nd:YLF Laser Light
Authors:
D. Bergstrom, Mid Sweden University; Ostersund Sweden
John Powell, Lulea University of Technology; Lulea Sweden
Alexander Kaplan, Lulea University of Technology; Lulea Sweden
Presented at PICALO 2008

The absorptance of real metallic engineering surfaces used in Laser Material Processing depends strongly upon the particular surface conditions, including the degree of roughness and oxidation. In this paper the influence of surface topography on Nd:YAG/Nd:YLF laser absorptance has been studied, both experimentally and theoretically, on a set of randomly selected as-received metallic engineering surfaces. The surfaces were sputter-coated with a thin layer of gold to eliminate differences in surface chemistry and oxidation. The absorptance was measured using integrating sphere reflectometry and compared to calculations from 3D ray-tracing simulations of AFM-scanned images of the surfaces. The results have increased the understanding of how surface roughness influences the laser-workpiece coupling efficiency.