Patent ID: 8310670

Claim:
A method for removal of a contaminant substance from a porous stone monument using nondestructive means, comprising: (a) identifying regions of said contaminant substance embedded on said porous stone monument; (b) characterizing a plurality of physical properties of said contaminant embedded on said porous stone monument; (c) exposing said contaminant embedded on said porous stone monument to irradiation from a laser characterized by a wavelength, a pulse length, a repetition rate, and a laser energy fluence determined and optimized for a given contaminant-porous stone system based on said plurality of physical properties of said contaminant including its predominant composition and thickness, (d) removing said contaminant by (a) automatically identifying regions of said contaminant deposited on said porous stone monument using Fourier transform Raman spectrometry, (b) automatically characterizing said contaminant thickness using Fourier transform Raman spectrometry, and (c) exposing said contaminant to irradiation from a Nd:YAG laser characterized by a wavelength greater than 200 nm; and (e) adaptively evaluating the cleaning results by quantifying in-situ the remaining thickness of said contaminant.