Application Research Of X-ray Phase Contrast Imaging Based On Laboratory Light Source

X-ray phase contrast imaging has been attracting increasing attention in recent years.The object is imaged by detecting the phase change of the X ray passing through the object.This method overcomes the shortcomings of traditional absorption imaging which is unable to detect weak-absorbing materials,it should find broad application in medicine,non-destructive testing and material science et al.Several methods of phase-contrast imaging,including crystal interferometer phase-contrast imaging,diffraction enhanced imaging,in-line phase-contrast and differential phase-contrast based on Talbot interferometer,have been developed.The requirement of X-ray source in crystal interferometer imaging and diffraction enhanced imaging(DEI)is strict and fabricate of optical instrument focusing X-ray is a challenge.So far method of DEI only can be performed with synchrotron source,so the application is restricted.Compared with other methods,in-line phase-contrast and differential phase-contrast are easily performed in conventional laboratory and very widely used because of their moderate requirement on coherence.So this article takes the two methods as the main research content.The in-line phase-contrast imaging was originally carried out in the synchrotron source,but the method can also be carried out under the micro-focal spot X-ray source.The micro-focal spot X-ray source has a good coherence,but the luminous flux is very low.In order to solve the conflict between brightness and spatial coherence,a X-ray source with one-dimensional coherence is proposed in this article.The new X-ray source has a special focal spot where one side is small enough to ensure the spatial coherence and the perpendicular side is big enough to provide sufficient X-ray flux.In the direction of long side,the long size of focal spot will result in losing the image details.Consequently,an algorithm of superposition and rotation,in which many images with different rotation angles are added together,is proposed to retrieve the lost information.Talbot-lau and inverse Talbot-lau methods have been developed so far in differential phase-contrast imaging.In this article,we find the actual function of the analyzer grating in the Talbot-Lau interferometer is segmenting the self-images of the phase grating and choosing integral areas,which make sure that each period of self-images in one detector pixel contributes the same signal to the detector.Furthermore,in the case of the lack of an analyzer grating,the shifting curves are still existent in theory as long as the number of fringes in non-integral in a detector pixel,which is a sufficient condition for creating shifting curve.This method can shorten the system length,is applicable to large period gratings,and can use the detectors with large pixels and large field of view.In addition,the experimental arrangement can be simplified due to the lack of an analyzer grating.Then we use this method in biological samples(chicken feet)for the imaging experiment.Finally,the phase-contrast image is more clear and the structure information is richer than the previous published papers.