Influence of laser pulse shape on dry laser cleaning

The influence of laser pulse shape and pulse duration on dry laser cleaning is investigated by means of combined experimental and theoretical approaches. Possibilities to enhance damage-free particle removal efficiency by adjusting the temporal parameters of laser irradiations are discussed. The numerical description predicts that the removal of sub-micron particles by excimer lasers occurs in the 'quasi-static' inertia force regime. Experiments are based on an electro-optic gating system capable of switching off either leading or trailing edges of an excimer laser pulse. It is demonstrated that the inertia force corresponding to the pulse trailing front may play a role in laser cleaning but not as the dominant mechanism. Both the surface temperature and the expansion dynamics of materials are calculated in order to examine their role in dry laser cleaning. This study helps to determine the dominant mechanism responsible for particle removal by nanosecond laser pulses.