Numerical Simulation of Micro-Flow Surface Smoothing of Fused Silica by CO₂ Laser

Micro-flow smoothing of fused silica surface with CO₂ lasers were numerically simulated. Two types of laser intensity distribution, namely Gaussian and top-hat, were modeled on various surface morphology. In the models, the surface tension and Marangoni effect were taken into account. The results show that surface tension and Marangoni effect acts synergically whereas surface tension dominates the resultant surface in our simulated conditions. Top-hat intensity is conducive to smoothing of fused silica glass. In addition, surfaces with both periodic and random topography can be smoothed. Under the 585.69 W/cm² power density, the best roughness (RMS) of Gaussian and top-hat is 2.85 nm and 2.48 nm respectively (initial roughness > 700 nm).