Automated shaping of laser-induced nanoripples on freeform surfaces
Poster presented at 10th International Laser Symposium & International Symposium »Tailored Joining«, February 27 - 28, 2018, International Congress Center Dresden
Since many years, there is a strong interest in realizing special surface properties combined with the goal to specifically control the surface function of parts. One approach to realize such specific modifications is the fabrication of small micro- and nanostructures that are able to change the properties of a surface. Especially on freeform surfaces, micro- and nanostructures can be fabricated efficiently by laser structuring since the laser can be integrated in a machine tool and thereby operates as a completely automated system solution. Laser-induced periodic ripple structures with a periodicity at the nanoscale are able to modify optical appearance, design, tribology, wetting and the cellular response of a part . Their orientation is related to the polarization direction of the incident laser radiation . To exploit their properties for industrial applications, it is necessary to produce these nanostructures on freeform parts and to control their alignment. Here, a novel system solution based on a liquid crystal polarization rotator is presented that allows for the automated manipulation of the polarization direction and is therewith suitable to control the lateral shape of the ripple structures on freeform surfaces . It is synchronized by a CAM software that controls in addition the laser, the laser scanner, the dynamic beam expander and the machine axes. Several example structures are shown that have been fabricated with this system and demonstrate the production possibilities and limits. In summary, the software solution for the automated alignment of self-organized nanostructures allows a precise, specific fabrication of these structures what is demonstrated with several examples. As a conclusion, it provides a first step towards the industrial application of these kind of structures on freeform parts for surface functionalization.