Molten pool dynamics effects in the fabrication of microstructures by Direct Laser Interference Patterning
Direct laser interference patterning (DLIP) is a well-known technique for producing functional surfaces based on topographical patterns with distinct sub-micro and micrometer-sized features at industrially acceptable fabrication speeds. Furthermore, this method has been successfully implemented on different materials, including metals, ceramics and polymers. Therefore, the capability to create different types of structures is vital for addressing new technological fields, including the automobile industry, medicine and aerospace industry, where functionalities such as superhydrophobicity, reduced friction, and antibacterial behavior among others are of high demand.
To extend the variety of structures that can be achieved with DLIP, further strategies have been developed that implement the control of interfering beams polarisation or phase. However, these additional elements increment the complexity of the system, which is highly undesirable for industrial applications.
In this study, we demonstrate alternative techniques for producing different structure shapes using a standard DLIP setup with four interfering laser beams and picosecond laser pulses (70 ps). By perfectly controlling the processing parameters such as the laser fluence and number of pulses, new periodic structures were fabricated on the surface of the stainless steel, which are controlled by the dynamics of the molten material. The produced patterns were characterized using confocal and scanning electron microscopy methods.