Laser Engraving Reflective Metals to Create Scanner Readable Barcodes

Laser marking of metals and plastics is one of the most widespread of all laser materials processing techniques used throughout the industrial sectors. One remaining challenge is the creation of scanner readable marks on highly reflective materials such as aluminium without the aid of a surface coating. In previous work the authors have presented a novel technique employing a high average power diode pumped solid-state Qswitched laser to locally change the surface roughness, creating high contrast regions between highly scattering laser roughened marks and the unmarked reflective substrate. In this paper the effect of surface modification is quantified and analysed for aluminium, and the techniques are transferred and adapted to other widespread industrial materials such as stainless and galvanized steel. In this way the authors demonstrate the applicability of this laser technique for a range of reflective metals. Applications such as traceability and security are discussed for high volume industrial sectors such as automotive manufacture.