Ultra-Short Pulsed Laser Marking and Coloration of Metals with Segmented Pixel Parameter Transformation

Abstract

Ultra-short pulsed laser modification points to novel coloration possibilities on a broad range of materials using laser induced periodic surface structures, plasmonic nanoparticles, and thermal oxidation as principles. Here, a general parameter-dependent laser path calculation routine for marking and coloration of complex images is presented. The original image is imported, dependent on size and resolution, down sampled and dithering applied. The color map attained from a laser parameter study is registered and the computer-aided manufacturing routine maps the color space to nearest neighbors of the original image. Thereafter, the laser paths with the adjacent parameters are computed and the numerical code generated. A complex colored pixel graphic is transformed and high-contrast marked in black and grey-scale on a stainless steel plate. Moreover, to demonstrate the capabilities, a titanium alloy is ultra-short pulsed laser colored. A colorful image proves this approach with a pixel size of below 40 μm and no observable cross talk between the colors.