Focal zone engineering with hollow spatially variable waveplates applicable in laser micromachining

Abstract

The ultrashort pulsed laser micromachining of transparent and opaque materials has become a mature technology providing microscale accuracy. While the ultrashort laser sources are being constantly developed with growing average power or more complex pulse temporal control, studies in the spatial domain can also lead to improving the performance i.e., higher process speed, better fabrication quality, etc. By purposely transforming the Gaussian beam of the laser output to a custom beam shape we are able to improve speed and quality in many laser micromachining tasks, where micro-welding of various materials is one of them. In this work, we apply custom hollow spatially variable waveplates based on nanograting technology (manufactured by Workshop of Photonics) that help to form curved or flat intensity distribution beams. Using numerical modeling and experimental research we will demonstrate beam transformations that could have an impact on enhancing the micro-welding process in terms of reduced stress or better heat dissipation.