The Laboratoire de Recherche des Monuments Historiques (LRMH) examined problems raised by the cleaning of historic monuments, and more precisely the cleaning of stone, and attempted to develop a cleaning process using laser rays called photonic disincrustation. Two teams collaborated on this project: the Institut Régional de Promotion de la Recherche Appliquée (IREPA-LASER) developed the method and its technology; the LRMH was in charge of efficiency control and compatibility with the special demands of historic monuments conservation. Gives an account of the present state of research and expected future developments.