{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,2]],"date-time":"2025-11-02T06:15:29Z","timestamp":1762064129750,"version":"build-2065373602"},"reference-count":31,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2022,8,30]],"date-time":"2022-08-30T00:00:00Z","timestamp":1661817600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"H2020 Laserlab Europe [EC-GA 871124]","award":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"],"award-info":[{"award-number":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"]}]},{"name":"POR FSE 2014\u20132020 Giovanis\u00ec of the Tuscany Region (Italy)","award":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"],"award-info":[{"award-number":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"]}]},{"name":"H2020 FETOPEN Dynamic project","award":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"],"award-info":[{"award-number":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"]}]},{"name":"NSRF 2014\u20132020 BIOIMAGING-GR","award":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"],"award-info":[{"award-number":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"]}]},{"name":"HELLAS CH","award":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"],"award-info":[{"award-number":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"]}]},{"name":"INNOVAPROTECT","award":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"],"award-info":[{"award-number":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"]}]},{"name":"Operational Program \u201cCompetitiveness, Entrepreneurship, and Innovation,\u201d","award":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"],"award-info":[{"award-number":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"]}]},{"name":"Greece and the European Union (European Regional Development Fund)","award":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"],"award-info":[{"award-number":["2663","249795","EC-GA-863203","MIS 5002755","MIS 5002735","MIS 5030524"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Imaging"],"abstract":"<jats:p>The new reflectance set-up configuration extended the applicability of the photoacoustic (PA) imaging technique to art objects of any thickness and form. Until now, ultrasound gel or distilled water have been necessary as coupling mediums between the immersion-type transducer and the object\u2019s surface. These media can compromise the integrity of real artwork; therefore, known applications of reflectance PA imaging have been limited to only experimental mock-ups. In this paper, we evaluate an alternative non-invasive PA coupling medium, agar gel, applied in two layers of different consistency: first, rigid\u2014for the protection of the object\u2019s surface, and second, fluid\u2014for the transducer\u2019s immersion and movement. Agar gel is widely used in various conservation treatments on cultural heritage objects, and it has been proven to be safely applicable on delicate surfaces. Here, we quantify and compare the contrast and signal-to-noise ratio (SNR) of PA images, obtained in water and in agar gel on the same areas, at equal experimental conditions. The results demonstrate that the technique\u2019s performance in agar is comparable to that in water. The study uncovers the advanced potential of the PA approach for revealing hidden features, and is safely applicable for future real-case studies.<\/jats:p>","DOI":"10.3390\/jimaging8090235","type":"journal-article","created":{"date-parts":[[2022,8,31]],"date-time":"2022-08-31T00:13:56Z","timestamp":1661904836000},"page":"235","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Agar Gel as a Non-Invasive Coupling Medium for Reflectance Photoacoustic (PA) Imaging: Experimental Results on Wall-Painting Mock-Ups"],"prefix":"10.3390","volume":"8","author":[{"given":"Antonina","family":"Chaban","sequence":"first","affiliation":[{"name":"National Institute of Optics\u2014Italian National Research Council, Largo E. Fermi 6, 50125 Florence, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9938-3472","authenticated-orcid":false,"given":"George J.","family":"Tserevelakis","sequence":"additional","affiliation":[{"name":"Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, Plastira 100, Vassilika Vouton, 70013 Heraklion, Crete, Greece"}],"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, Plastira 100, Vassilika Vouton, 70013 Heraklion, Crete, Greece"}],"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, Plastira 100, Vassilika Vouton, 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\u2014Italian National Research Council, Largo E. Fermi 6, 50125 Florence, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,8,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Tserevelakis, G.J., Chaban, A., Klironomou, E., Melessanaki, K., Striova, J., and Zacharakis, G. (2021). Revealing Hidden Features in Multilayered Artworks by Means of an Epi-Illumination Photoacoustic Imaging System. J. Imaging, 7.","DOI":"10.3390\/jimaging7090183"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Chaban, A., Tserevelakis, G.J., Klironomou, E., Fontana, R., Zacharakis, G., and Striova, J. (2021). Revealing Underdrawings in Wall Paintings of Complex Stratigraphy with a Novel Reflectance Photoacoustic Imaging Prototype. J. 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