Effect of Laser Radiation on 19th Century Paper

The effect of laser radiation on a German geographic map printed in 1846 is investigated. The sample is irradiated with pulsed and continuous wave radiation (cw) at a wavelength of 532 nm and fluences of 5 and 3 kJ/cm 2, respectively. A visible decrease in discoloration resulting from the pulsed irradiation is demonstrated. ATR FTIR and fluorescence spectroscopy are used for diagnostics. The discolouration of the laser irradiated map after five years and the corresponding spectral changes are discussed.