Analytical model for CO_2 laser ablation of fused quartz

This paper reports the development of an analytical model, with supporting experimental data, which quite accurately describes the key features of ${\mathrm{CO}}_2$ laser ablation of fused silica glass. The quantitative model of nonexplosive, evaporative material removal is shown to match the experimental data very well, to the extent that it can be used as a tool for ablative measurements of absorption coefficient and vaporization energy. The experimental results indicated that a minimum of $12\mathrm{MJ}{\mathrm{kg}}^{-1}$ is required to fully vaporize fused quartz initially held at room temperature, which is in good agreement with the prediction of the model supplied with input data available in the literature. An optimal window for the machining of fused quartz was revealed in terms of pulse duration 20–80 μs and ${\mathrm{CO}}_2$ laser wavelength optimized for maximum absorption coefficient. Material removal rates of 0.33 μm per $\mathrm{J}{\mathrm{cm}}^{-2}$ allow for a high-precision depth control with modest laser stability. The model may also be used as a parameter selection guide for ${\mathrm{CO}}_2$ laser ablation of fused silica or other materials of similar thermophysical properties.