Preliminary development of radioscopy detector for specific industrial radiography inspection

Abstract

A digital X-ray detector based on fluoroscopy concept was designed and fabricated. The detector consists of digital monochrome video camera, first surface mirror and fluorescence screen. Preliminary quantitative tests of the camera were performed to measure the optimum setup and height of the system. The tests performed were modulation transfer function (MTF) and signal to noise ratio (SNR). The most optimum setup was used as the main basis for the development of the whole radioscopy system. The digital monochrome video camera was attached with scientific lenses with standard C-mount type and connected to the PC by using fire wire cable and controlled by software for image acquisition. Two different MTF values at 20% modulation were measured on two different assembly types; camera with lens, camera with lenses and controlled X-radiation. The MTF20% for camera with lens assembly is 4.23 lp/mm and the complete setup at 114kV, 3mA is 2.5 lp/mm. The lower spatial resolution was due to the un-sharpness caused by the fluorescence screen which has MTF20% of 2.8 lp/mm at 130 lux. The radioscopy system was later evaluated with a European Norm on specific system classes. This paper highlights further finding on the radioscopy and its capability in identifying discontinuities found in welding.