Real-time monitoring and expert control of laser cleaning.

In order to achieve the sound cleaned surface as well as to control the process with an automatic manner, real-time monitoring based on acoustic, optical and chromatic approaches have been carried out in the laser cleaning processes. Diverse materials such as copper, marble, paper have been used for the removal of the surface contaminants by a Q-switched Nd:YAG laser in this study. The process was monitored by detecting the acoustic wave emitted from the surface during laser cleaning. Direct surface monitoring was carried out by sensing the reflected light from the surface. Chromatic modulation technique based on tristimulus detection was also used for investigating the laser-induce plume during cleaning. In addition, the expert system based on fuzzy rule base has been developed not only to predict the surface damage beforehand but also to control the laser cleaning process effectively. These techniques may provide unique information for characterising the process as well as a promise of successful applications of laser cleaning in real practical fields.