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

Abstract

We presents the results of study of focusing and imaging properties of double-lens system for hard x-ray radiation consisting of two Fresnel zone plates (ZP) made from silicon.We demonstrate for the first time the phenomenon of focusing by two crystal ZP located at significant distance from each other. We investigate by both theoretically and experimentally the peculiarities of intensity distribution at the focal plane during a scan by second ZP normally to the optical axis of the system. We investigate as well the intensity distribution along the optical axis for our double-lens system from crystal ZP.We realize experimentally a registration of the focused image of the object by means of double-lens system based on ZP. Measurements are performed on the beam line BM-5 of the European Synchrotron Radiation Facility (ESRF) at the x-ray energy 9.4 keV. We elaborate a computer program for theoretical simulation of the optical properties of x-ray double-lens system based on ZPs. A calculation is made by convolution of transmission function and Kirchhoff propagator in paraxial approximation by means of Fast Fourier Transformation.

Angular spectrum simulation of X-ray focusing by Fresnel zone plates

“…Another interesting problem that can be studied by this wavefield propagation computer routine is the case of two FZPs stacked in the near-field (Maser et al, 2002;Aristov et al, 2007;Snigireva et al, 2007;Feng et al, 2007). Especially in the hard X-ray regime, the use of a FZP pair is an interesting approach to achieve higher diffraction efficiency and overcome the limitations on the production of high-aspect-ratio diffractive optical elements imposed by the nanofabrication technology.…”

“…We illustrate the versatility of the code for modeling several FZP geometries and materials and for computing important parameters such as the diffraction efficiencies and the shapes of the focal spots. In addition, we use the routine to consider the case of two high-resolution FZPs (outermost zone width Ár > 30 nm) stacked in the near-field (Maser et al, 2002;Aristov et al, 2007;Snigireva et al, 2007;Feng et al, 2007). In the hard X-ray regime, increasing the effective zone height by coupling two FZPs is a feasible solution to achieve higher diffraction efficiencies that may not be reachable by a single diffractive element when limitations of the FZP fabrication process exist.…”