The two-wavelength laser cleaning methodology; theoretical background and examples from its application on CH objects and monuments with emphasis to the Athens Acropolis sculptures

The two-wavelength laser cleaning methodology has been introduced and developed in order to meet demanding cleaning challenges in CH. The innovation lies on the combined use of two laser beams, allowing thus control of the laser ablation effective regimes towards an efficient and safe cleaning result. A series of studies on technical samples and real fragments aimed at defining and refining this methodology in order to ensure that the original surface, including its details and historic traces, will be safeguarded. In this paper related research and applications will be presented in an attempt to enlighten the associated laser ablation processes, as well as the potential cleaning applications in CH field. Laser-assisted removal of pollution accumulations from the Athens Acropolis monuments and sculptures is a unique highlight on the use of this methodology in practice. IESL-FORTH in collaboration with the Acropolis Restoration Service and the Acropolis Museum has developed an innovative cleaning methodology and a prototype laser cleaning system, which since 2002 have been introduced to the everyday conservation practice and will be presented in this paper.