Imaging performance of a CaWO4/CMOS sensor

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) scree...

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Main Authors: Niki Martini, Vaia Koukou, George Fountos, Ioannis Valais, Ioannis Kandarakis, Christos Michail, Athanasios Bakas, Eleftherios Lavdas, Konstantinos Ninos, Georgia Oikonomou, Lida Gogou, George Panayiotakis
Format: Article
Language:English
Published: Gruppo Italiano Frattura 2019-09-01
Series:Fracture and Structural Integrity
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Online Access:https://www.fracturae.com/index.php/fis/article/view/2614
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Summary: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.
ISSN:1971-8993