{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,21]],"date-time":"2026-02-21T14:41:20Z","timestamp":1771684880028,"version":"3.50.1"},"reference-count":35,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2021,9,10]],"date-time":"2021-09-10T00:00:00Z","timestamp":1631232000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"H2020 Laserlab Europe","award":["EC-GA 871124"],"award-info":[{"award-number":["EC-GA 871124"]}]},{"name":"H2020 FETOPEN project \u201cDynamic\u201d","award":["EC-GA-863203"],"award-info":[{"award-number":["EC-GA-863203"]}]},{"name":"NSRF 2014-2020 \u201cBIOIMAGING-GR\u201d","award":["MIS 5002755"],"award-info":[{"award-number":["MIS 5002755"]}]},{"name":"HELLAS CH","award":["MIS 5002735"],"award-info":[{"award-number":["MIS 5002735"]}]},{"name":"INNOVAPROTECT","award":["MIS 5030524"],"award-info":[{"award-number":["MIS 5030524"]}]},{"name":"Joint Advanced Education Project RS4Art, co-financed by the Tuscany Region with the resources of the POR FSE 2014-2020 - Axis A Employment, \u201cGiovanis\u00ec\u201d as part of the Intervention program called \u201cCNR4C\u201d.","award":["249795"],"award-info":[{"award-number":["249795"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Imaging"],"abstract":"<jats:p>Photoacoustic imaging is a novel, rapidly expanding technique, which has recently found several applications in artwork diagnostics, including the uncovering of hidden layers in paintings and multilayered documents, as well as the thickness measurement of optically turbid paint layers with high accuracy. However, thus far, all the presented photoacoustic-based imaging technologies dedicated to such measurements have been strictly limited to thin objects due to the detection of signals in transmission geometry. Unavoidably, this issue restricts seriously the applicability of the imaging method, hindering investigations over a wide range of cultural heritage objects with diverse geometrical and structural features. Here, we present an epi-illumination photoacoustic apparatus for diagnosis in heritage science, which integrates laser excitation and respective signal detection on one side, aiming to provide universal information in objects of arbitrary thickness and shape. To evaluate the capabilities of the developed system, we imaged thickly painted mock-ups, in an attempt to reveal hidden graphite layers covered by various optically turbid paints, and compared the measurements with standard near-infrared (NIR) imaging. The obtained results prove that photoacoustic signals reveal underlying sketches with up to 8 times improved contrast, thus paving the way for more relevant applications in the field.<\/jats:p>","DOI":"10.3390\/jimaging7090183","type":"journal-article","created":{"date-parts":[[2021,9,10]],"date-time":"2021-09-10T10:31:34Z","timestamp":1631269894000},"page":"183","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Revealing Hidden Features in Multilayered Artworks by Means of an Epi-Illumination Photoacoustic Imaging System"],"prefix":"10.3390","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9938-3472","authenticated-orcid":false,"given":"George J.","family":"Tserevelakis","sequence":"first","affiliation":[{"name":"Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, GR-70013 Heraklion, Crete, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Antonina","family":"Chaban","sequence":"additional","affiliation":[{"name":"National Institute of Optics INO-CNR, 50125 Florence, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Evgenia","family":"Klironomou","sequence":"additional","affiliation":[{"name":"Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, GR-70013 Heraklion, Crete, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kristalia","family":"Melessanaki","sequence":"additional","affiliation":[{"name":"Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, GR-70013 Heraklion, Crete, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0790-4689","authenticated-orcid":false,"given":"Jana","family":"Striova","sequence":"additional","affiliation":[{"name":"National Institute of Optics INO-CNR, 50125 Florence, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Giannis","family":"Zacharakis","sequence":"additional","affiliation":[{"name":"Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, GR-70013 Heraklion, Crete, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"758","DOI":"10.1002\/lpor.201200060","article-title":"Photoacoustic microscopy","volume":"7","author":"Yao","year":"2013","journal-title":"Laser Photon. Rev."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"300","DOI":"10.1111\/jmi.12396","article-title":"Hybrid photoacoustic and optical imaging of pigments in vegetative tissues","volume":"263","author":"Tserevelakis","year":"2016","journal-title":"J. Microsc."},{"key":"ref_3","unstructured":"Wang, L.V., and Wu, H.-I. (2012). Biomedical Optics: Principles and Imaging, John Wiley and Sons."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1016\/j.pacs.2014.04.002","article-title":"Sensitivity of photoacoustic microscopy","volume":"2","author":"Yao","year":"2014","journal-title":"Photoacoustics"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1016\/j.pacs.2016.01.002","article-title":"Bond-selective photoacoustic imaging by converting molecular vibration into acoustic waves","volume":"4","author":"Hui","year":"2016","journal-title":"Photoacoustics"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"100144","DOI":"10.1016\/j.pacs.2019.100144","article-title":"A review of clinical photoacoustic imaging: Current and future trends","volume":"16","author":"Attia","year":"2019","journal-title":"Photoacoustics"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"747","DOI":"10.1038\/s41598-017-00873-7","article-title":"Photoacoustic imaging reveals hidden underdrawings in paintings","volume":"7","author":"Tserevelakis","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"94","DOI":"10.1016\/j.ultras.2019.06.008","article-title":"Non-invasive photoacoustic detection of hidden underdrawings in paintings using air-coupled transducers","volume":"98","author":"Tserevelakis","year":"2019","journal-title":"Ultrasonics"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e12289","DOI":"10.1111\/str.12289","article-title":"Uncovering the hidden content of layered documents by means of photoacoustic imaging","volume":"55","author":"Tserevelakis","year":"2019","journal-title":"Strain"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"919","DOI":"10.1364\/OL.44.000919","article-title":"Combined photoacoustic imaging to delineate the internal structure of paintings","volume":"44","author":"Tserevelakis","year":"2019","journal-title":"Opt. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"123102","DOI":"10.1063\/1.5022749","article-title":"Photoacoustic signal attenuation analysis for the assessment of thin layers thickness in paintings","volume":"123","author":"Tserevelakis","year":"2018","journal-title":"J. Appl. Phys."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"515","DOI":"10.1007\/s40766-020-00011-6","article-title":"Reflectance imaging spectroscopy in heritage science","volume":"43","author":"Striova","year":"2020","journal-title":"Riv. Nuovo Cim."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1007\/s00339-011-6689-1","article-title":"Advances in multispectral and hyperspectral imaging for archaeology and art conservation","volume":"106","author":"Liang","year":"2012","journal-title":"Appl. Phys. A"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2070","DOI":"10.1021\/acs.accounts.6b00048","article-title":"Reflectance Hyperspectral Imaging for Investigation of Works of Art: Old Master Paintings and Illuminated Manuscripts","volume":"49","author":"Cucci","year":"2016","journal-title":"Acc. Chem. Res."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1587\/transinf.2018AWI0003","article-title":"Simultaneous reproduction of reflectance and transmittance of ink paintings","volume":"102","author":"Asada","year":"2019","journal-title":"IEICE Trans. Inf. Syst."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"6133","DOI":"10.1364\/OPEX.13.006133","article-title":"En-face optical coherence tomography\u2014A novel application of non-invasive imaging to art conservation","volume":"13","author":"Liang","year":"2005","journal-title":"Opt. Express"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1007\/s00339-011-6687-3","article-title":"Optical coherence tomography: Its role in the non-invasive structural examination and conservation of cultural heritage objects-A review","volume":"106","author":"Targowski","year":"2012","journal-title":"Appl. Phys. A"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"453","DOI":"10.1007\/s40766-021-00023-w","article-title":"Nonlinear optical microscopy for artworks physics","volume":"44","author":"Castillejo","year":"2021","journal-title":"Riv. Nuovo Cim."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3407","DOI":"10.1364\/OE.17.003407","article-title":"TeraHertz imaging of hidden paint layers on canvas","volume":"17","author":"Adam","year":"2009","journal-title":"Opt. Express"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"257","DOI":"10.1007\/s00339-011-6691-7","article-title":"Nonlinear imaging and THz diagnostic tools in the service of Cultural Heritage","volume":"106","author":"Filippidis","year":"2012","journal-title":"Appl. Phys. A"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"12665","DOI":"10.1038\/ncomms12665","article-title":"Terahertz time-gated spectral imaging for content extraction through layered structures","volume":"7","author":"Heshmat","year":"2016","journal-title":"Nat. Commun."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1016\/j.sab.2013.07.009","article-title":"Mobile depth profiling and sub-surface imaging techniques for historical paintings\u2014A review","volume":"88","author":"Alfeld","year":"2013","journal-title":"Spectrochim. Acta B"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1154\/1.1649963","article-title":"X-rays in art and archaeology: An overview","volume":"19","author":"Schreiner","year":"2004","journal-title":"Powder Diffr."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1186\/s40494-016-0105-2","article-title":"Jackson Pollock\u2019s Number 1A, 1948: A non-invasive study using macro-x-ray fluorescence mapping (MA-XRF) and multivariate curve resolution-alternating least squares (MCR-ALS) analysis","volume":"4","author":"Martins","year":"2016","journal-title":"Herit. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"760","DOI":"10.1039\/c3ja30341a","article-title":"A mobile instrument for in situ scanning macro-XRF investigation of historical paintings","volume":"28","author":"Alfeld","year":"2013","journal-title":"J. Anal. At. Spectrom."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"3684","DOI":"10.1364\/BOE.391026","article-title":"Application of the generalized contrast-to-noise ratio to assess photoacoustic image quality","volume":"11","author":"Kempski","year":"2020","journal-title":"Biomed. Opt. Express"},{"key":"ref_27","first-page":"745","article-title":"The generalized contrast-to-noise ratio: A formal definition for lesion detectability","volume":"67","author":"Rindal","year":"2019","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"100207","DOI":"10.1016\/j.pacs.2020.100207","article-title":"Towards non-contact photoacoustic imaging [review]","volume":"20","author":"Hosseinaee","year":"2020","journal-title":"Photoacoustics"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"4151","DOI":"10.1364\/OL.35.004151","article-title":"Remote photoacoustic imaging on solid material using a two-wave mixing interferometer","volume":"35","author":"Berer","year":"2010","journal-title":"Opt. Lett."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"051105","DOI":"10.1063\/1.4928123","article-title":"Non-contact optoacoustic imaging with focused air-coupled transducers","volume":"107","author":"Pang","year":"2015","journal-title":"Appl. Phys. Lett."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"4","DOI":"10.1109\/TBME.2016.2605451","article-title":"Optical Detection of Ultrasound in Photoacoustic Imaging","volume":"64","author":"Biqin","year":"2017","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1038\/s41377-018-0036-7","article-title":"Looking at sound: Optoacoustics with all-optical ultrasound detection","volume":"7","author":"Wissmeyer","year":"2018","journal-title":"Light Sci. Appl."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"20170262","DOI":"10.1098\/rsta.2017.0262","article-title":"Spectral unmixing techniques for optoacoustic imaging of tissue pathophysiology","volume":"375","author":"Tzoumas","year":"2017","journal-title":"Philos. Trans. R. Soc. A"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"034106","DOI":"10.1117\/1.OE.59.3.034106","article-title":"Photoacoustic imaging to examine documents altered by black pens on paper in forensic science","volume":"59","author":"Suzuki","year":"2020","journal-title":"Opt. Eng."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"e201900218","DOI":"10.1002\/jbio.201900218","article-title":"Naturally safe: Cellular noise for document security","volume":"12","author":"Krmpot","year":"2019","journal-title":"J. Biophotonics"}],"container-title":["Journal of Imaging"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2313-433X\/7\/9\/183\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:00:09Z","timestamp":1760166009000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2313-433X\/7\/9\/183"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,9,10]]},"references-count":35,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2021,9]]}},"alternative-id":["jimaging7090183"],"URL":"https:\/\/doi.org\/10.3390\/jimaging7090183","relation":{},"ISSN":["2313-433X"],"issn-type":[{"value":"2313-433X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,9,10]]}}}