The Design Of High-Resolution X-ray Imaging System Based On MCP

At present,the resolution ratio of most Chinese-made X-ray imaging systems is about 5lp/mm,we can not observe the subtle internal structures of some objects with them. The application of X-ray image intensifiers with Micro-Channel Plate (MCP) in the X-ray imagining system can improve the imaging quality of the system greatly. But the noise will be intensifed along with the useful information,which will influent the resolution ratio and clarity of the imaging quality of the system.On the imaging system with constant gain,many changes of imaging conditions will influent the imaging quality of the system greatly.Based on this background, after studying the X-ray imaging and Low-Light-Level imaging theory, the paper designed a high-resolution X-ray imaging system by using the high-resolution X-ray intensifier as the converting installation which converted X-ray image to visible light image,and using the nondistortion transport property of optical fiber taper,took it as optical relay component(X-ray image intensifier optical fiber panel fluorescent screen was coupled to photosensitive surface of CCD). The high-resolution X-ray imaging system designed in the paper has some advantages of high resolution(reached 12 ),adaptive MCP voltage,less cubage, lighter weight and portability.It could satisfy the demand of small domain medical imaging and nondestructive testing.The hardware structure of the imaging system have been analysed and the capability parameters of the detailed apparatus have been presented in this paper. The paper also tested and researched the main property index of the system, which including: resolution, penetration sensitivity, dynamic range and the response homogeneity,the relationship between the image grey mean value and the MCP voltage, and the MTF of the system.Besides,the paper analysed the factors that influent the resolution ratio of the system,the optical magnify times of the system and the minimum drawback size that the system can detect.The experiment result showed that the imaging system designed in the paper could detect many slight drawbacks that common CR and DR could not detect.In addition, according to the relationship of MCP voltage and the gain of the system, the author used an adjustable high-voltage power supply to supply to the MCP of the X-ray intensifier. Finally, based on the relationship between the grad amplitude and the edge of the image,the paper investigated the objective image quality evaluation theory, and advanced an image quality evaluating method that using the grad amplitude accumulation as an image quality evaluating index, and analyzes and evaluates the image quality under defferent MCP voltage with the very method.