Fabrication of diffraction based security elements using direct laser interference patterning

Product piracy impacts wide areas of the global economy resulting in multi-billion dollar losses per year. Therefore, product protection technologies are required to produce security elements with high flexibility and complexity. In this work, the fabrication of diffraction-based security elements, so called grating cell arrays, using direct laser interference patterning is presented. Ultraviolet two-beam interference patterning is used to structure line-like gratings into 80 µm in diameter spots with spatial periods ranging from 0.7 µm to 2.2 µm on PET substrates. The developed grating cell arrays are generated by the combination of several holographic surface gratings with variable spatial period and pattern orientation. The stored security information can be visualized by illumination with a coherent light source such as a laser pointer.