1. Articles from raffaella fontana

    1-4 of 4
    1. Photoacoustic signal attenuation analysis for the assessment of thin layers thickness in paintings

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

      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 thicknesses on glass substrates were realized for the specific application. After characterization by Optical Coherence Tomography 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 ...

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    2. Using Optical Coherence Tomography to Reveal the Hidden History of The Landsdowne Virgin of the Yarnwinder by Leonardo da Vinci and Studio

      Using Optical Coherence Tomography to Reveal the Hidden History of The Landsdowne Virgin of the Yarnwinder by Leonardo da Vinci and Studio

      Optical coherence tomography (OCT) was used for non‐invasive examination of a well‐known, yet complex, painting from the studio of Leonardo da Vinci in combination with routine imaging in various bands of electromagnetic radiation. In contrast with these techniques, OCT provides depth‐resolved information. Three post‐processing modalities were explored: cross‐sectional views, maps of scattering from given depths, and their 3D models. Some hidden alterations of the painting owing to past restorations were traced: retouching and overpainting with their positioning within varnish layers as well as indications of a former transfer to canvas.

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    3. Optical and spectroscopic tools for evaluating Er:YAG laser removal of shellac varnish

      Optical and spectroscopic tools for evaluating Er:YAG laser removal of shellac varnish

      We report on tests to remove naturally and artificially aged shellac varnish by laser and traditional chemical cleaning from the substrates of mural paintings. Optical tools were used for the evaluation of cleaning processes, in particular laser microprofilometry to assess the changes in the surface morphology and time-domain confocal optical coherence tomography (OCT) to evaluate varnish thickness. The cleaning assessment was integrated with molecular characterization provided by portable Fourier transform infrared spectroscopy operating in reflectance mode, and colorimetric measurements. This complete analytical approach led to optimized laser-based cleaning tests at 1.9 and 2.6 J/cm 2 in the ...

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    4. Optical coherence diagnostics for painting conservation

      Raffaella Fontana, Marco Bellini, Chiara Corsi et al. One of the most important and sometimes controversial stages of the conservation process is surface cleaning: decisions have to be made regarding partial or complete removal of varnish. Technical considerations include selection of a method that allows a great deal of control in the cleaning process ... [Proc. SPIE Int. Soc. Opt. Eng. 6618, 661808 (2007)] published Mon Jul 16, 2007.
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    1-4 of 4
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    Optical and spectroscopic tools for evaluating Er:YAG laser removal of shellac varnish Photoacoustic signal attenuation analysis for the assessment of thin layers thickness in paintings Using Optical Coherence Tomography to Reveal the Hidden History of The Landsdowne Virgin of the Yarnwinder by Leonardo da Vinci and Studio Optical Coherence Tomography: Critical Tool to Manage Expectations after Cataract Extraction Improving the characterization of ex vivo human brain optical properties using high numerical aperture optical coherence tomography by spatially constraining the confocal parameters Choroidal, macular and ganglion cell layer thickness assessment in Caucasian children measured with spectral domain optical coherence tomography Examination of retinal vascular density changes via optical coherence tomography angiography in patients with glaucoma 3D reconstruction of coronary artery bifurcations from coronary angiography and optical coherence tomography: feasibility, validation, and reproducibility Age- and refraction-related changes in anterior segment anatomical structures measured by swept-source anterior segment OCT The evaluation of juvenile ocular hypertension by optical coherence tomography angiography Superficial capillary perfusion on optical coherence tomography angiography differentiates moderate and severe nonproliferative diabetic retinopathy Autologous neurosensory free-flap retinal transplantation for refractory chronic macular hole—outcomes evaluated by OCT, microperimetry, and multifocal electroretinography