In order to investigate the principle and fabrication technique of Fresnel zone plates (FZPs)

a diffractive optical element used in X-ray imaging with the best resolution currently is presented. A theoretical analysis of the spatial resolution depending on the outermost zone width is given. An analytical expression of the diffraction efficiency in terms of thickness and X-ray refractive index of the zone plate is also provided. Electron beam lithography combined with X-ray lithography is employed to fabricate FZPs. Experimental results indicate that the outermost zone width is 150 nm and the aspect ratio is 4

which satisfies the X-ray imaging system requirements of high resolution

high aspect ratio as well as high precision.