Grayscale Marking of Anodized Aluminium Plate by Using Picosecond Laser and Galvanometer Scanner

In this work, we demonstrate the grayscale modifications of an anodized aluminium plate by using ultra-short laser pulses. The measurement and analysis results on influence of the laser marking process parameters on the blackness of marking obtained are presented. The study was conducted for the aluminium plate with the transparent anodizing Al 2 O 3 coating by using a commercially available industrial picosecond laser and galvanometer scanner. The grayscale of marking was changed by scanning the laser beam focused at the boundary of the coating and aluminium sheet without damaging the transparent coating. The scanning speed and mean laser power was varied in order to enhance the blackness of the marking.