Security optimization of artefacts laser cleaning

Abstract

Laser techniques have become irreplaceable in solving a wide variety of conservation problems. For the last thirty years, lasers have been used in the diagnostic process, in the process of removing undesirable layers, as well as in repairing damages of cultural heritage objects. Because of the complexity of artifacts, traditional cleaning methods in many cases have partial success. Laser cleaning shows certain advantages such as: high selectivity, precision, efficiency and reliability in application in different types of materials. There are also certain risks for cleaning objects, and the studies of process optimization are the subject of a number researches. This paper presents the methodology and results of the application of infrared thermography for the continuous monitoring of temperature distribution on the surface of metal objects during laser irradiation. A large number of experiments were performed using Nd: YAG laser for cleaning. The obtained results were verified by the results of the numerical simulation of heat propagation in the base material. It has been shown that infrared thermography can eliminate damage to the base material, which is of special importance in the laser cleaning of priceless value artifact.

Laserske tehnike su postale nezamenjive u rešavanju najrazličitijih konzervatorskih problema. Zadnjih tridesetak godina koriste se u procesu dijagnostike stanja, u procesu uklanjanja nepoželjnih slojeva, kao i u sanaciji oštećenja na predmetima kulturnog nasleđa. Zbog složenosti artefakata, tradicionalne metode čišćenja, u velikom broju slučajeva, imaju delimičnog uspeha. Lasersko čišćenje pokazuje određene prednosti kao što su: velika selektivnost, preciznost, efikasnost i pouzdanost u primeni kod različitih vrsta materijala. Postoje i određeni rizici po predmete čišćenja, te je optimizacija procesa predmet velikog broja istraživanja. U ovom radu su prikazani metodologija i rezultati primene infracrvene termografije za kontinualni monitoring raspodele temperature na površini metalnih objekta za vreme ozračavanja laserom. Izvršen je veliki broj eksperimenata, u kojima se Nd:YAG laser koristi za čišćenje. Dobijeni rezultati termogarfijom su verifikovani rezultatima numeričke simulacije širenja toplote u osnovnom materijalu. Pokazano je da se primenom infracrvene termografije mogu eliminisati oštećenja na osnovnom materijalu, što je od posebnog značaja kod artefakata neprocenjive vrednosti.