Large Scale Ultrafast Laser Micro Texturing with Multi-Beams

Today ultrashort pulse lasers (USP lasers) are already widely used to realize highly precise microstructures directly in nearly any material. Despite of today's availability of high power ultrashort pulse lasers (up to several hundred watts), it is still a challenge to structure large surface areas, as required on embossing rollers, within an acceptable processing time for industrial production. A newly developed high compact ps-laser with repetition rates of up to 8MHz and an average power of up to 500W was distributed into 8 parallel beamlets by a diffractive optical element (DOE). Each of the single beams in the array is controlled by an acousto optical modulator (AOM). The beam array was focused on a cylinder surface with spot sizes of 10m. Based on this initial set up, a further improved optical systems with 16 single beams has been designed to increase ablation speed and productivity. The beams have a distance of 20m (8 beamlets) respective 80m (16 beamlets) from spot to spot. Integrated in an ultra-high precision cylinder engraving system, the spots were synchronized with a precision of <1m. Different functional surface geometries have been realized on an embossing roller as a master, which is used for the replication of the structures in roll-to-roll (R2R) processes. With this setup, functional structures as e.g. reduction in friction, improved soft touch or light guiding elements can be generated on large surfaces within short processing times.