Enhancing laser materials processing efficiency: dynamic beam shaping and parallelization strategies

Adaptable intensity distributions and parallelization of laser beams are of interest to enhance the processing efficiency for more and more laser applications. The parallelization of laser beams based on beam splitting diffractive optical elements (DOE) and a 2D galvanometer scanner is state of the art. The use of a beam splitting DOE in combination with a 2D galvanometer scanner introduces problems that need to be overcome to achieve a satisfactory result: a scanner-induced distortion of the DOE-generated spot matrix occurs in the working plane and the spot matrix twists as a function of the deflection angle of the scanner mirrors. Common setups employ either static relay lenses for multi-beam systems or additional actuators to increase spot position accuracy. We combine these two approaches in a cascaded optical system using a dynamically rotatable DOE. The achievable accuracy is evaluated with a simulation tool developed specifically for a typical optical configuration for multi-beam laser materials processing. In addition, a first functional prototype with a rotating DOE is demonstrated. The cascaded rotating DOE offers potential for flexible parallel laser processes.