Ultrafast laser cleaning of museum artifacts

A new method oflaser ablation, having high pulse-rate of the order of MHz, with short ps and sub-ps pulses, has been recently developed at the ANU. As a preliminary test for the short-pulse ablation applied to art conservation for selective removal of unwanted surface layers, we used the ps laser to clean brass samples coated with contaminant layers such as rust, paint and wax. We demonstrated the laser cleaning system with 2^nd (λ₂=532nm) and 4^th (λ₄=266nm) harmonics of a Nd: YVO₄ ultra-fast laser, combined with a constantvelocity scanning system. Great flexibility in cleaning the surfaces selectively was demonstrated by removal of the wax coating from the black-painted surface without altering the black paint surface sub-structure. Major conservation and restoration challenges were considered where ultrafast laser cleaning might playa vital role.