Niki Martini https://orcid.org/0000-0002-9525-2010 Vaia Koukou https://orcid.org/0000-0003-1722-744X George Fountos Ioannis Valais https://orcid.org/0000-0001-6808-0252 Ioannis Kandarakis Christos Michail https://orcid.org/0000-0001-5863-8013 Athanasios Bakas Eleftherios Lavdas Konstantinos Ninos https://orcid.org/0000-0001-5933-0133 Georgia Oikonomou Lida Gogou George Panayiotakis


The aim of this study was to investigate the modulation transfer function (MTF) and the effective gain transfer function (eGTF) of a non-destruc­­tive testing (NDT)/industrial inspection complementary metal oxide semi­conductor (CMOS) sensor in conjunction with a thin calcium tungstate (CaWO4) screen. Thin screen samples, with dimensions of 2.7x3.6 cm2 and thick­ness of 118.9 μm, estimated from scanning electron microscopy-SEM im­ages, were extracted from an Agfa Curix universal screen and coupled to the active area of an active pixel (APS) CMOS sensor. MTF was assessed using the slanted-edge method, following the IEC 62220-1-1:2015 method. MTF values were found high across the examined spatial frequency range. eGTF was found maximum when CaWO4 was combined with charge-coupled devices (CCD) of broadband anti-reflection (AR) coating (17.52 at 0 cycles/mm). The com­bi­nation of the thin CaWO4 screen with the CMOS sensor provided very pro­mis­ing image resolution and adequate efficiency properties, thus could be also con­sidered for use in CMOS based X-ray imaging devices, for various applications.


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    SI: Research activities of the Greek Society of Experimental Mechanics of Materi

    How to Cite

    Martini, N., Koukou, V., Fountos, G., Valais, I., Kandarakis, I., Michail, C., … Panayiotakis, G. (2019). Imaging performance of a CaWO4/CMOS sensor. Frattura Ed Integrità Strutturale, 13(50), 471–480. https://doi.org/10.3221/IGF-ESIS.50.39