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Fig. 6 | Heritage Science

Fig. 6

From: Listening to laser light interactions with objects of art: a novel photoacoustic approach for diagnosis and monitoring of laser cleaning interventions

Fig. 6

Hybrid PA and optical monitoring during the laser-assisted removal of encrustation from stonework. a Cross-correlation between PA waveforms recorded after the incidence of Nth and 1st pulse, which is used as reference (first 6 pulses are presented). The 1st pulse curve (black color) corresponds to an autocorrelation function. An optimum laser fluence is applied at 0.8 J/cm2. b Maximum amplitude of cross-correlation function graph estimated for 15 pulses. c Percentage change of cross-correlation maximum amplitude; the peak indicates the pulse for which the marble substrate has been reached. d Optical images of the laser spot recorded for 15 sequential pulses. Red border indicates the point (5th pulse) where the maximum change has been observed according to (c). e Percentage change of cross-correlation maximum amplitude estimated for 15 pulses at 3 different fluences. Figure adapted from [61]

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