CCD-based high resolution digital radiography system for nondestructive evaluation

Film radiography has long served the aerospace industry as a principal method for hardware flaw detection. Although excellent in performance, this method is extremely time consuming, labor intensive, costly, and is unsuitable for real time inspections. Modern digital radiographic systems overcome some of these difficulties but are also limited in terms of speed of operation due to persistence of the sensor and a problematic tradeoff between the X-ray detection efficiency and spatial resolution. We are developing an innovative X-ray imaging detector consisting of a novel microstructured CsI scintillator coupled to a fiberoptic taper-based CCD. Thin-film deposition techniques, previously developed to produce thin, structured CsI screens have been extended to fabricate CsI screens, up to 450 mg/cm² (1,000 μm) in thickness. These sensors are suitable to provide high detection efficiency with high image quality for NDE applications. A prototype high energy imaging system was constructed by integrating these screens into a fiber-optic-based CCD camera. The performance was compared to that of the same system using a standard polycrystalline phosphor for NDE imaging applications. The experimental evaluations were carried out at Scientific Measurement Systems, Inc., Austin, TX