An optical field regulation method for waterjet-guided laser: Reducing taper and improving deep-processing capability

Waterjet-guided laser (WGL) processing technology has the advantages of low thermal damage, no contact stress and ultra-fine processing. However, the energy distribution of the existing technology in the laminar flow water column is still characterized by Gaussian distribution, which leads to taper effect in the processing of thick plate materials and affects the deep-processing capability. To address these shortcomings, a novel waterjet laser-field regulation (WLR) method is proposed in this paper. Optical simulation and coupling experiments confirm the method's ability to modulate the energy within the waterjet into a circular distribution, which solves the problem of low power density near the surface of the waterjet. Waterjet-guided laser cutting experiments were conducted based on the WLR method, and the taper was significantly reduced compared to the conventional WGL. At a power of 12 W, the taper was reduced from 5.85° to 2.28°, a reduction of 61 %. In terms of processing depth, the WLR method cuts slightly lower groove depths with a low number of cuts, but as the number of cuts increases, the groove depth steadily increases and exceeds that of the conventional WGL. At 500 cuts with a laser power of 20 W, the groove depths obtained by the WLR method increased by 115 % compared to that of the conventional WGL. This study has important implications for the processing of thick materials by waterjet-guided laser.