Laser cleaning of metal artifacts: Microstructural, chemical and optical fiber-based analysis

Laser cleaning was carried out on artificially aged copper specimens, comparing the result of different laser irradiance values and different number of passes. The cleaned surfaces were initially characterized by optical and scanning electron microscopy, X-ray diffraction and X-ray photo-electron spectroscopy. These analyses showed that near-IR laser cleaning successfully removed the corrosion products from the surface of the metallic artifacts. After cleaning at higher irradiance or after repeated cleaning steps, a slight surface alteration was observed. In the view of a future real-time laser cleaning process monitoring, the samples were also characterized by optical fiber spectroscopy. A signature in the spectral reflectance could be used to distinguish between metal, corrosion products layer and cleaned surface.