On the Influence of Thermal Lensing During Selective Laser Melting

Multi kilowatt single mode lasers are increasingly being used in Selective Laser Melting (SLM), typically with the aim of improving productivity. However, the high power densities present in the optical path lead to a thermally induced focal shift i.e. thermal lensing. Whilst thermal lensing has been studied for many processes, its impact on parts produced by SLM is currently unknown. Therefore this work discusses the characteristics of a thermally induced focal shift supplemented by a method for the compensation of this effect. In addition, SLM parts with and without thermal lensing compensation are compared in order to show the effect on final part quality.