Product Code: ICA12_M1003

Characterisation of Interaction Phenomena in High Repetition Rate Femtosecond Laser Ablation of Metals
Authors:
Joerg Schille, Laser Institute at the Univ. of Applied Sciences Mittweida, The Photon Science Institute, The Univ. of Manchester; Mittweida Germany
Lutz Schneider, Laser Institute at the Univ. of Applied Sciences Mittweida; Mittweida Germany
Lars Hartwig, Laser Institute at the Univ. of Applied Sciences Mittweida; Mittweida Germany
Udo Loeschner, Laser Institute at the Univ. of Applied Sciences Mittweida; Mittweida Germany
Robby Ebert, Laser Institute at the Univ. of Applied Sciences Mittweida; Mittweida Germany
Patricia Scully, The Photon Science Institute, The Univ. of Manchester; Manchester Great Britain
Nicholas Goddard, The Photon Science Institute, The Univ. of Manchester; Manchester Great Britain
Horst Exner, Laser Institute at the Univ. of Applied Sciences Mittweida; Mittweida Germany
Presented at ICALEO 2012

High repetition rate femtosecond lasers combine high qualities, accuracy and efficiency with high processing speeds and seem to be a promising tool in micro machining and rapid tooling. However first applications show novel phenomena in ultra short pulse laser processing, such as heat accumulation, particle shielding and material melting, which affect the machining process considerably. In this paper ultra short pulse laser processing of metals using a high repetition rate fibre laser is presented in order to characterise the laser matter interaction phenomena more in detail. The influence of the parameters pulse energy, repetition rate and lateral pulse distance on the ablation rate was determined by measuring the ablation depths. The ablation mechanism is discussed by means of results obtained experimentally related to both results achieved in a simplified temperature calculation and photographs taken with an intensified ultra high speed camera. A significant effect of the repetition rate as well as thermo-physical properties of the irradiated materials on the amount of ablated material and ejected particle has been found. Appropriate processing parameters are derived to obtain high quality machining results with a minimum thermal load together with high machining throughputs. Finally machining outcomes will be presented.