高质量X射线检测数字化成像及图像采集

X射线数字成像检测是工业无损检测的新技术.非胶片实时数字成像检测以其高效率、低成本,特别是数字图像的可交换性和存储方便等特点成为射线检测的发展趋势.通常使用的由射线像增强器、视频摄像机、图像采集卡和计算机组成的系统成像质量差且只能在低能X射线下使用,作者经过反复研究和实验,研制了基于单晶闪烁屏和科学级CCD相机的可用于高、低能X射线高分辨率、高对比灵敏度数字成像检测系统.介绍了整个检测系统的组成,设计了科学级制冷CCD相机、预处理电路、A/D转换电路、微机EPP方式快速数据采集电路和软件等.给出了某铝铸件(厚150mm)在加速器高能X射线下的成像结果.实验证明该系统比普通像增强器和视频相机组成的系统具有适应射线能量范围宽和成像质量好的优点(成像时间长一些).系统的空间分辨率大于3lp/mm, 检测物体50mm(等效钢厚)以上时,对比度灵敏度小于1%.

Digital imaging and its data quick acquisition in high quality X-ray testing

X-ray digital imaging testing technology is a new method of nondestructive testing. Non-film real time digital radiography , which has high efficiency and low cost, especially the characteristics of digital image exchangeability and storage convenience, has become the development direction. The commonly used system consisting of a X-ray image intensifier, a video camera, an image acquisition card and a computer has the disadvantage of low imaging quality and only being used at low X -ray energy. By repetitive investigating and testing, a high spatial resolution and high contrast sensitivity system based on crystal scintillation and scientific CCD camera has been developed, which can be used both at low energy and high energy. This paper introduces the constitution of the system, including the scientific grade CCD camera which must be refrigerated, an output signal pre-processing circuit of CCD, A/D circuit, and quick data acquisition circuits using the EPP mode of computer and softwares. An aluminium casting (150mm) image obtained by the system at accelerator high energy X-ray is offered.The experimental results show the system has merits of adapting a wider X-ray energy range and imaging quality better than the system based on an image intensifier and a video camera(imaging time longer than the latter). The spatial resolution of the system is over 3lp/mm, the contrast sensitivity, when the thickness of the object to be inspected exceeds 50mm equivaled steel thickness, is below 1%.