Evaluation of molten zone in glass welding using ultra-short pulsed laser

Fusion welding is well known as the most promising technique in glass joining, since joining can be accomplished without any intermediate layer and mechanical contact. High precision, small heat-affected zone (HAZ) and small shock-affected zone (SAZ) by ultra-short pulsed laser make it possible to perform the process with minimal damages to the surrounding area. However, there still remained a lot of things to be clarified in this process, since glass materials are very sensitive to temperature gradients and available in different thermal properties. In this study, molten zones created by ultra-short pulsed laser in borosilicate glass and fused silica glass were evaluated. Laser irradiation was carried out inside the glass under various processing conditions. Molten zone was observed visually, and its mechanical strength was measured using three points bending test.