Application of wave optical simulations to focusing x-ray multilayers

Recently, a new software tool was developed at the ESRF that can perform wave optical simulations on curved multilayer optics. It is based on a Takagi-Taupin approach and the two beam approximation. Outside the multilayer structure the beam is propagated by phase ray tracing and by solving the Kirchhoff integral. Extended sources can be modelled by superposition of point sources. The spatial coherence can be varied by the degree of random averaging of amplitude and phase of these point sources and by their distribution in space. This work deals with applications of this formalism to realistic cases of existing or planned multilayer based nanofocusing mirrors. It also attempts to explore fundamental physical limitations and how they are reproduced by the model. Open questions will be addressed and potential future investigations will be outlined.