Faster Femtosecond Laser Processing using a Dual-Focus SLM Emulated Lens

The generation of multiple beams is an established method to increase the processing speed of advanced laserbased material processing techniques. This multi-foci approach has shown promising results in laser micromachining, scanning microscopy, optical data storage, or optical tweezer arrays. Of particular interest is its application to manufacturing bigger objects where laser treatment is required over surfaces on the centimetre scale or larger. Using a Spatial Light Modulator (SLM), such parallelisation has been studied over the last few years by splitting the input beam into multiple beams (up to 1000 beams [1]) for simultaneous machining on a plane (x-y) perpendicular to the propagation axis (z). This method is primarily based on holographic femtosecond laser processing [2] where computer-generated holograms (CGH) are displayed on an SLM. Further applications include phase distortion and lens aberration correction [3], or for four-dimension light shaping [4]. The SLM provides unique features for dynamic pulse shaping, more efficient use of the laser energy, or the machining of complex shapes.