Sub-mm sized embossing roller patterning using direct laser interference

Periodic patterned surfaces can be used to provide unique surface properties in applications, such as biomaterials[1], surface engineering, photonics[2] and sensor systems. Such periodic patterns can be produced using Direct Laser Interference Patterning (DLIP). Laser processing tools are showing significant advantages due to a precise modification of the surfaces with remote and contact-less operation, high flexibility, precise energy deposition and without contamination. DLIP allows the rapid production of different periodic micron and submicron patterns on large flat but also on curved areas like embossing rollers used in the Roll-to-Roll (R2R) process. By using DILP seamless structured embossing rollers can be created which will lead to defect free imprints across the entire substrate length. During DILP the primary laser is typically split into two or more beams that later intercept with a certain angle and interfere resulting in a periodic intensity distribution. This variation of intensity minima and maxima is then transferred to the substrate surface by ablation processes resulting in e.g. line-, hole- or pillar-like micron/submicron structures. By using this technology structure sizes from 150 nm to 50 µm can be achieved. Fig.1a shows a stainless steel cylinder with 2 µm period line-like structures and Fig.1b shows a patterned diamond like carbon (DLC) with feature sizes of 75 nm.[3,4]