new mechanisms for laser cleaning using Nd:YAG sources
of Cultural Heritage 4 (2003) 59s–64s
Watkins a, Carmel Curran a , Jong-Myung Lee b
Laser Group, Department of Engineering, University of
Liverpool, Brownlow Street, Liverpool L69 3GH, UK
b Laser Application Group, IMT Co. Ltd., Yongin P.O.
Box 2525, Kyunggi-Do 449-860, Republic of Korea
new methods for the laser cleaning using a Q-swihed Nd:YAG
laser have been developed and investigated. These offer
increased efficiency and reduction in possible substrate
damage for a wide range of substrate/encrustation combinations.
In angular laser cleaning, it is shown that by controlling
the angle of incidence of the cleaning laser, significant
improvement in the efficiency of cleaning can be achieved
when compared with conventional cleaning with a normal angle
of incidence. A model is proposed to explain this effect.
In laser shock cleaning, a completely different approach
is presented. By aligning the incoming laser beam to be
horizontal to the surface to be cleaned but close to it
and selecting operating parameters that lead to a breakdown
of the air above the object to be cleaned, a laser-induced
shock wave is produced that is very much more effective
than conventional normal incidence cleaning in removing
surface pollutants. However, because the laser does not
come into contact with the substrate, this method significantly
minimises the potential for substrate damage. Again, a model
for the cleaning process is presented. The results for the
operation of both methods on polluted marble are presented.
© 2003 Éditions scientifiques et médicales Elsevier SAS.
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