LAUSR

Abstract In order to study the influence of air gap and focus position on the quality of ps-laser glass-to-glass welding we implemented a method of detecting the air gap between glass surfaces based on optical thin film interference. The method allows real-time optimization of the welding process. We measure the air gap between glass surfaces to be bonded and the laser focal position, which are set as the constraint conditions affecting the nonlinear self-focusing of the laser beam. The processing parameters of picosecond laser welding are determined and the welding strength and the morphology of bonded zone are detected and observed. Laser welding with good performance can be achieved with an air gap of 2 μm. SEM microscopy shows that the bonding region between two glass surfaces is very smooth in the vicinity of the tear-drop shaped cross-sectional structure of the welded glass. A tensile strength inspection fixture is designed, and we measured a tensile fracture strength of over 30 MPa for the welded glass. Through confocal microscope analysis, the width and depth of fracture morphology of welded samples are shown to change with air gap, which is consistent with the theoretical analysis.