微焦点X射线源相衬成像是利用微焦点X射线源透过样品后携带的相位信息对样品内部结构成像．通过获取相面上的强度信息利用相位复原方法可以得到物体内部的相位信息．获取了不同放大倍数下的蚂蚁图像,通过强度传播方程(Transport of Intensity Equation,TIE)方法得到了蚂蚁的相衬图像,采用边缘可见度(Edge Visibility)方法和熵法比较了不同放大倍数下的成像效果以及复原前后图像质量．
In-line x-ray phase contrast imaging has attracted much attention due to two major advantages： its effectiveness in imaging weakly absorbing materials, and the simplicity of its facilities. In this paper a comprehensive theory based on Wigner distribution developed by Wu and Liu [Med. Phys. 31 2378-2384 （2004）] is reviewed. The influence of x-ray source and detector on the image is discussed. Experiments using a microfocus x-ray source and a CCD detector are conducted, which show the role of two key factors on imaging： the tube voltage and tube current. High tube current and moderate tube voltage are suggested for imaging.
For weakly absorbing materials, image contrast can be enhanced by phase contrast in formation. The effectiveness of the in-line phase contrast technique relies on its ability to record intensity data which contain information on the x- ray＇s phase shift. Four kinds of approaches to the relationship between intensity distribution and phase shift axe reviewed and discussed. A micro-focal x-ray source with high geometrical magnification is used to acquire phase contrast images. A great improvement on image quality is shown and geometrical parameters axe modified for comparison between different imaging positions.
