Excimer laser induced surface modifications and matter interaction using double-pulse-technique (DPT)

Excimer laser radiation is excellently absorbed by metallic and ceramic surfaces. However, under certain conditions the use of excimer lasers in materials processing may be limited by plasma formation, plasma reflection and absorption mechanisms. This may restrict possible excimer laser applications to be carried out using certain beam sources (e.g. specified pulse duration or pulse energy) or beam qualities. The aim of the current investigations is to improve and to enhance the coupling efficiency by modifying the pulse length of the laser system. One possible method to change the pulse length and pulse energy very quickly is to build up two externally triggered laser sources. The master timing system, developed at the ATZ-EVUS facilities is used to switch both lasers simultaneously. The pulse energy as well as the pulse length can be doubled using this system. Fundamental investigations have been carried out to determine the influence of the delay between the two laser pulses on the plasma formation, propagation and the plasma absorption. The plasma absorption and the correspondent removal rates are correlated to the chosen delay value. First experimental results will be given to demonstrate the potential of this technology especially for the excimer laser treatment of metals.