Polarized reflectance of aluminum and nickel to 532, 355 and 266 nm Nd:YAG laser beams for varying surface finish

Polarized reflectances of Al and Ni treated by two types of surface finish, namely lapping and electro-polishing, for 532, 355, and 266 nm wavelength laser beams, are measured and compared with the theoretical polarized reflectance. For metals treated by lapping, there exists a distinct trend coming from the surface directionality that results from the mechanical surface finish. The reflectance for the case where the surface directionality is parallel to the electric field of incident beam is higher than the case where surface directionality and electric field are perpendicular to each other. This trend is not observed in metals treated by electro-polishing having no surface directionality. Our studies provide reference to the surface finish effects on the reflectance of Al and Ni for various wavelength beams, providing insight into the improvement of laser processing efficiency by adjusting surface directionality of metals and polarization of beam.

► Linearly polarized reflectances of Al and Ni for 532, 355, and 266 nm beams are measured.
► Two different surface finishes (lapping and electro-polishing) are considered.
► Absorptance is lower when surface directionality is parallel to electric field of incident beam.
► Absorptance is higher when surface directionality is perpendicular to electric field of beam.