Sphere-to-Plate Glass Welding using Picosecond-Laser Radiation

Welding of a spherical shaped glass beads with the diameter of 0.7 mm to a float glass plate by using picosecond laser irradiation was investigated. The glass bead itself acts as focusing lens and should be considered as a part of optical system. The different number of pulses, repetition rate and average laser power were applied to estimate the joint strength dependence on the laser process parameters. Modeling of transient thermal fields induced by laser irradiation was performed in order to evaluate a possible defect formation. Two types of crack-free welding regimes were found, namely, the point welding with a low number of laser pulses and a weak joint and the fusion welding when irradiation lasts up to one second. The joint area is significantly larger and the glass bead can withstand higher compression stress which is important for application in vacuum isolated glasses. The processes still need to be optimized in terms of productivity.