Scientific Results

Photoacoustic signal attenuation analysis for the assessment of thin layers thickness in paintings

Year: 2018

Authors: Tserevelakis G. J., Dal Fovo A., Melessanaki K., Fontana R., Zacharakis G.

Autors Affiliation: Foundation for Research and Technology Hellas, Institute of Electronic Structure and Laser, N. Plastira 100, Heraklion, Crete, Greece; Consiglio Nazionale delle Ricerche – Istituto Nazionale di Ottica, Largo Enrico Fermi 6, 50125,
Firenze, Italy; Università degli Studi di Firenze, Dip. Chimica, Via della Lastruccia 3, 50019, Sesto Fiorentino,
Firenze, Italy

Abstract: This study introduces a novel method for the thickness estimation of thin paint layers in works of art, based on photoacoustic signal attenuation analysis (PAcSAA). Ad hoc designed samples with acrylic paint layers (Primary Red Magenta, Cadmium Yellow, Ultramarine Blue) of various thickness on glass substrates were realized for the specific application. After characterization by OCT imaging, samples were irradiated at the back side using low energy nanosecond laser pulses of 532 nm wavelength. Photoacoustic waves undergo a frequency-dependent exponential attenuation through the paint layer, before being detected by a broadband ultrasonic transducer. Frequency analysis of the recorded time-domain signals allows for the estimation of the average transmitted frequency (ATF) function, which shows an exponential decay with the layer thickness. Ultrasonic attenuation models were obtained for each pigment and used to fit the data acquired on an inhomogeneous painted mockup simulating a real canvas painting. Thickness evaluation through PAcSAA resulted in excellent agreement with cross-section analysis by conventional brightfield microscope. The results of the current study demonstrate the potential of the proposed PAcSAA method for the non-destructive stratigraphic analysis of painted artworks.

Journal/Review: JOURNAL OF APPLIED PHYSICS

Volume: 123 (12)      Pages from: 123102-1  to: 123109-9

KeyWords: Frequency domain analysis; Frequency estimation; Optical tomography; Paint; Signal analysis; Stratigraphy; Substrates; Thickness measurement; Ultrasonic testing; Ultrasonic transducers, Broadband ultrasonic transducers; Cross-section analysis; Exponential attenuation; Nanosecond laser pulse; Photoacoustic signals; Stratigraphic analysis; Thickness estimation; Ultrasonic attenuation, Time domain analysis
DOI: 10.1063/1.5022749

Citations: 7
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