Laser precision surface sculpting of 2D diffractive optical structures on metals

A laser surface sculpting technique, which uses a commercial nanosecond UV laser at 355nm to drive a highly localised melting and melt flow process, is demonstrated for the production of reflective 2D diffractive optical structures on martensitic stainless steel and nickel samples. It is shown that this lasertexturing process can be used to generate 10×10μm² pixels with depths ranging from 150nm to 500nm. Either single or multiple pulses are used to generate each feature via hydrodynamic surface melt deformations, dependent on the dimensions of the features required, material properties, and the laser parameters. To demonstrate the viability of the process for the generation of 2D diffractive structures, it was used to create 2D matrices on mechanically polished stainless steel samples. The diffraction efficiency of these samples is measured and compared with a Fraunhofer diffraction model.