Abstract
A method to monitor laser cleaning is presented in this paper. During laser cleaning of contamination, particles are generated and/or ejected from a substrate based on laser ablation and laser-induced fast thermal expansion of contaminants and/or the substrate. An airborne particle counter is used to detect the particles ejected from the substrate during laser cleaning at the same time as the irradiation of the laser beam. The cleaning threshold, cleaning efficiency, cleanliness of substrate and ablation threshold of substrate can be monitored by particle detection.