Novel 6-axis articulated ultrashort pulsed laser robotic system using a hollow-core fiber for flexible micromachining

We report for the first time on the realization, comprehensive characterization and application of a 6-axis articulated laser robot using a flexible beam guidance of ultrashort laser pulses via a non-polarization-maintaining hollow-core fiber. Measurements during and after a movement of the fiber-based ultrashort pulsed laser robotic (USPLR) system reveal that fundamental beam characteristics such as transmission, beam pointing and diameter and pulse duration are only marginally affected after passing through the hollow-core fiber. In addition, we studied the application of the USPLR system to laser cutting of brass foils and a printed circuit board (PCB) substrate in a single-path mode and optimize the process with respect to the heat-affected zone and kerf width by varying the applied pulse energy and robot speed. Our findings reveal that heat accumulation plays a significant role for the cutting quality at slow robot speeds of up to 20 mm/s, whereas a reduction of the kerf width down to about 7 µm is feasible. Furthermore, detected vibrations of the USPLR system with varying magnitude at different 3D spatial cutting positions result in oddness of the cutting edges of up to about 200 µm. Nevertheless, optimized process parameters result in a high cutting quality with a small heat-affected zone and a virtually straight and sharp cutting edges in a large processing area of 500 mm $$\times$$ 600 mm $$\times$$ 300 mm, highlighting the substantial potential of the fiber-based USPLR system for flexible and large-area 2D and 3D micromachining.