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., Bakas, A., Lavdas, E., Ninos, K., Oikonomou, G., Gogou, L. and Panayiotakis, G. (2019) “Imaging performance of a CaWO4/CMOS sensor”, Frattura ed Integrità Strutturale, 13(50), pp. 471–480. doi: 10.3221/IGF-ESIS.50.39.