Diffractive optics as beam-shaping elements for plastics laser welding

Abstract

Abstract. This work reviews the use of diffractive optics for beamshaping of high-power lasers ͑50-100 W͒ for welding and microwelding of plastics. While the use of lasers to weld plastics is well known, the use of diffractive optics to reshape lasers for welding of plastics has not been previously reported. By using inverse Fourier transformations diffractive lenses were designed and fabricated. An 80 W fiber laser with a wavelength of 1084 nm was coupled in air to the diffractive optical element ͑DOE͒ to shape the beam into predetermined patterns. These patterns were then reduced with standard optics to a desired size. Weld quality was assessed in terms of fidelity and replication of the original bitmap image that was used to design the DOE. Good results were obtained for both image fidelity and replication. In many cases the weld image retained the individual bitmap elements of the original artwork used to encode the DOE. It was also found that the overall efficiencies of the system were as high as 59% and weld times were less than 1 s. Weld joints were also determined to be relatively strong and weld circles as small as a few hundreds of m in diameter could be formed.

An inverse model for optimisation of laser heat flux distributions in an automated laser tape placement process for carbon-fibre/PEEK

“…Such optical systems are not only limited to uniform profiles, they can be customised with technologies such as freeform lens manufacturing [31,32]. Other methods for generating custom beam profiles include diffractive optical elements [33][34][35], geometric optics [36] or scanning mirrors [37]. Recent advances in Vertical-Cavity Surface-Emitting Laser (VCSEL) technology have lead to the development of compact NIR emitting modules with powers in the kilowatt range [38].…”