This paper presents a laser-based process for the direct generation of security markings (in the form of reflective phase holograms) on the surface of metals. In order to achieve optically smooth holograms, we use a nanosecond pulsed laser operating at a 355 nm wavelength. This approach allows the metal surface to be structured, either by melting or the combination of melting and evaporation, with the required sub-micron depth control. The interaction between the UV 35 ns laser pulses and the surface of a 304-grade stainless steel, 99% pure nickel and two nickel-chromium Inconel® alloys is investigated in details and described in this paper.
|Publication status||Published - 2014|
|Event||15th International Symposium on Laser Precision Microfabrication 2014 - Radisson BLU Hotel Lietuva, Vilnius, Lithuania|
Duration: 17 Jun 2014 → 20 Jun 2014
|Conference||15th International Symposium on Laser Precision Microfabrication 2014|
|Period||17/06/14 → 20/06/14|
Wlodarczyk, K. L., Ardron, M., Weston, N., Kidd, M., & Hand, D. P. (2014). Direct laser-writing of optical micro-structures for robust traceability marking of metal components. Paper presented at 15th International Symposium on Laser Precision Microfabrication 2014, Vilnius, Lithuania.