The paper presents a novel method for simultaneous transmission welding of polymers using a high power multimode fiber laser. The method utilizes a diffractive optical element which shapes the focused laser beam into the desired weld shape. This kind of optical device enables the use of high power multimode fiber laser which again gives a possibility to use sub-second welding times.
Weld quality was assessed in terms of strength (pull test) and visual appearance. The diffractive optics provides an even powerd istribution and only small part of power is lost on the zeroth order.
Design of diffractive element gives flexibility with the weld shapes and sizes but the drawback is that these parameters cannot be modified after the production of the element. Using the optics would be more advantageous if multiple parts could be welded at one shot because the part changing time will be a lot longer than the welding time. Results show good weld quality, superior welding speed and high weld strength compared to quasi-simultaneous laser welding of the same material.