Towards industrial application of ultrafast laser microwelding

We report continued progress towards industrialisation of picosecond laser welding of highly dissimilar materials; i.e. glasses to metals. The welding process relies on a tightly focussed 1030 nm 400 kHz 5.9 ps laser system. This tight focus ensures highly localised absorption through a combination of linear and non-linear processes at or around the desired weld plane [1,2]. Suitable preparation of the two materials ensures that the plasma formed through this absorption is unable to escape and is confined to the interface region. This plasma mixes, cools and ultimately forms a weld between the two materials.
We will report on recent progress in increasing the reliability of the weld process, with a particular emphasis on the requirements for part preparation, surface cleanliness and calibration of the laser welding system. In addition we will present recent work on quantifying the optical retardation, which is directly related to the degree of stress induced into the part, through polariscopic measurements [3] with direct comparison to standard adhesive techniques. Finally we will report on recent work to expand the range of laser systems applicable for this highly industrially relevant process with an emphasis on reducing costs.