Study of optical properties of X-ray system based on two zone plates

Study of focusing and imaging properties of two Fresnel zone plates (ZP) system for hard X-rays is presented. A phenomenon is demonstrated for the first time of focusing by two ZP located at significant distance from each other. Peculiarities of intensity distribution at the focal plane during a scan by second ZP normally to the optical axis of the system as well as along the optical axis both theoretically and experimentally is investigated. A registration is realized experimentally on the beam line BM-5 ESRF (Grenoble, France) at E=9.4 keV of the focused image of the object. Computer program is elaborated for optical properties simulation using convolution of transmission function and Kirchhoff propagator in paraxial approximation by Fast Fourier Transform (FFT).