Structural colors with embedded anti-counterfeit features fabricated by laser-based methods

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

Abstract

Structural colors can be induced on metals not only to fabricate logos or decorative motives but also to embed anti-counterfeit features for product protection. In this study, stainless steel (EN 1.4301) plates are colorized by growing a thin oxide layer using direct laser writing (DLW) and hidden anti-counterfeit measures are included on their surfaces by direct laser interference patterning (DLIP) processing. The periodic microstructures resulting from the DLIP treatment have a spatial period of 1 µm and act as relief diffraction gratings, featuring a characteristic diffraction pattern. These microstructures are not visible to the human eye but are easily detectable upon shining a coherent beam on the surface. Furthermore, the reflectance over the visible spectrum of the colorized surfaces with and without the DLIP microtexture is measured, giving low differences in the color perception following the so-called “CIE L*a*b*” color space. Finally, a demonstrator is fabricated, in which colorized fields with and without the security features are shown.

Details

Original languageEnglish
Article number108012
Number of pages10
JournalOptics and Laser Technology
Volume151
Publication statusPublished - Jul 2022
Peer-reviewedYes

External IDs

WOS 000820998300005

Keywords

DFG Classification of Subject Areas according to Review Boards

Keywords

  • Anti-counterfeiting, Color perception, Direct laser interference patterning, Direct laser writing, Structural colors