Yakymets M. Improvement of the Technology for Cleaning the Surface of Paper Sheets of Early Printed Books Using Laser Radiation

The dissertation is devoted to solving a relevant scientific and applied problem, which consists in improving the technology for cleaning the surface of paper sheets of early printed books using pulsed laser radiation based on establishing the regularities of the influence of Nd:YAG irradiation parameters on the efficiency of contaminant removal and the safety of the paper substrate. For the first time, a method for evaluating laser cleaning regimes for paper sheets of early printed books has been developed on the basis of a parametric matrix, which makes it possible to carry out quantitative colorimetric control of changes in the optical properties of the paper substrate and contaminants depending on the wavelength, fluence level and number of laser passes. For the first time, standardized cartographic and cumulative representation of laser cleaning results has been introduced separately for wavelengths of 532 nm and 1064 nm, which ensured comparability of effects according to fluence level and number of passes within a unified experimental scheme. For the first time, the feasibility of including a mechanical criterion in the comprehensive verification of the safety of laser cleaning of early printed books has been substantiated as an additional means of detecting possible local weakening of the paper substrate after intensive pulsed irradiation. The procedure for experimental evaluation of the results of laser cleaning of paper sheets of early printed books has been improved by refining the rules for the comprehensive interpretation of colorimetric and visual-microscopic data. Keywords: early printed books, document preservation, paper aging, tensile strength, paper surface, laser technologies, energy transfer, analytic hierarchy process, fuzzy logic, factor alternatives, luminescence, optical properties, optical and thermodynamic interaction, laser emitters.