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2 Zeszyty Naukowe Instytutu Maszyn Przepływowych Polskiej Akademii Nauk w Gdańsku

2 2002

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Biblia Leopolity - konserwacja z użyciem lasera oraz badania papieru i wybranych zanieczyszczeń

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Kamińska A. , Bredal-Jørgensen J. , Ochocińska K. , Śliwiński G.

Zeszyty Naukowe Instytutu Maszyn Przepływowych Polskiej Akademii Nauk w Gdańsku

2002

tom nr 524/1483

157--171

Parts of the Polish oldest, illustrated Leopolita's Bible from XVI cent, are cleaned by the 532 nm Nd:YAG laser pulses and the results are analyzed by means of optical and scanning microscopy. Under mild irradiation conditions, i.e. for beam energy density from the range of 0.3-0.6 J/cm2, and pulse number not exceeding 15, the laser cleaning leads to positive results at locations where previously applied chemical treatment did not. This is confirmed by the microscopic observation and also by comparison of the respective fluorescence spectra obtained under laser excitation at 266 nm. It is shown, that for the case of laser application for cleaning of paper the careful selection of the applied wavelength, laser pulse energy and irradiation dose prevents the document and the paper substrate from unintended damage due to mechanical, thermal and photochemical effects.

Spektroskopia LIF oraz LIPS w diagnostyce i monitoringu laserowego oczyszczania dokumentów zabytkowych

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Ochocińska K. , Śliwiński G. , Kamińska A.

Zeszyty Naukowe Instytutu Maszyn Przepływowych Polskiej Akademii Nauk w Gdańsku

2002

tom nr 524/1483

139--156

Techniques of laser induced spectroscopy: LIF and LIPS for diagnostics and monitoring of laser cleaning of old paper documents are proposed and experimental examples of applications are discussed. The LIF spectra of the model and historical paper samples are recorded under different conditions, i.e. pulsed excitation at 266 nm and 532 nm (fourth and second harmonic of Nd:YAG laser), and at the cryogenic (10K) and room temperature, before and after cleaning by means of the laser (532 nm, 0.5 J/cm/} or by the chemical method. The presence of contamination reveals a marked effect on the spectra which also depend strongly on the sample cleaning history. For excitation at 266 mn the characteristic band structure of the paper is observed in the LIF spectra in agreement with previous experiments. Results of the LIPS monitoring of laser cleaning (532 nm, 0.5 J/cm2) of an archive book from XIX cent, covered by a dark, dust-like layer of contamination confirms the usefulness of the applied diagnostic method. Sharp emission lines recorded at 589.4, 616.4, 780 nm (Na I); 612.5, 644.2, 646.5, 649.7, 671, 714.9, 720.2 nm (Ca I); and 766.5, 769.9 nm (Mg I) are ascribed to the surface pollutants and their intensity decrease with successive pulses. The broad band centred at 616 nm, originates most probably from the substrate fluorescence with superimposed contamination peaks.