Laser cleaning of paper using Nd:YAG laser running at 532 nm

The paper reports on immediate effects of pulsed laser operating at 532 nm and fluences below 2.5 J cm –2 on soiled cellulose. The degree of polymerisation was determined viscometrically, while diffuse reflectance FTIR was used to gain insight into the changes in the chemical composition. Although no detectable immediate changes were observed after treatment of paper with laser beam at 532 nm, the irradiation of paper containing carbonaceous dirt resulted in significant discoloration of the treated substrate. The possible reasons for the extensive formation of yellow chromophores are discussed.