3D transient thermal modelling of laser microchannel fabrication in lime-soda glass

Laser-fabricated microchannels in glass offer a wide range of bioengineering and telecommunication applications. A 1.5 kW CO2 laser with 10.6 μm wavelength was used in this study to fabricate micorchannels on the surface of soda-lime glass sheets. A thermal model of the process was developed based on transient heat conduction due to a pulsed heat input. The resulting equation predicted the temperature distribution in the regions surrounding the laser focus. Temperature–time curves were drawn from those equations, which were useful in estimating the thermal history in the processed samples. The temperature distribution was also used to predict the channel geometry (based on the vaporisation temperature of glass). Most of the laser power used was consumed in bringing the glass to the vaporisation temperature. The model was able to predict the channel width, depth and surface roughness. These laser-fabricated channel characteristics were measured and compared to the results obtained from the thermal model. The laser power, frequency, pulse width and translation speed were the control parameters in both studies; hence a direct comparison was established between the model and the experimental results.