Advanced analysis and modelling methods has been an essential part of X-ray optics advances and X-ray techniques development at synchrotron light sources. These methods not only help researchers develop designs of X-ray sources and beamlines, diagnose and identify problems and issues in operations, but also enable advanced modelling and simulations of novel X-ray optics and experiments. Recent development rends in diffraction-limited sources and in coherence applications further illustrate the community interests and increased needs in advanced wavefront-based analysis and modelling capabilities. This presentation will provide an overview of this growing area of X-ray optics and techniques and its impact on synchrotron science in general.
Partially-coherent wavefront propagation calculations have proven to be feasible and very beneficial in the design of
beamlines for 3rd and 4th generation Synchrotron Radiation (SR) sources. These types of calculations use the framework
of classical electrodynamics for the description, on the same accuracy level, of the emission by relativistic electrons
moving in magnetic fields of accelerators, and the propagation of the emitted radiation wavefronts through beamline
optical elements. This enables accurate prediction of performance characteristics for beamlines exploiting high SR
brightness and/or high spectral flux. Detailed analysis of radiation degree of coherence, offered by the partially-coherent
wavefront propagation method, is of paramount importance for modern storage-ring based SR sources, which, thanks to
extremely small sub-nanometer-level electron beam emittances, produce substantial portions of coherent flux in X-ray
spectral range. We describe the general approach to partially-coherent SR wavefront propagation simulations and present
examples of such simulations performed using "Synchrotron Radiation Workshop" (SRW) code for the parameters of
hard X-ray undulator based beamlines at the National Synchrotron Light Source II (NSLS-II), Brookhaven National
Laboratory. These examples illustrate general characteristics of partially-coherent undulator radiation beams in low-emittance
SR sources, and demonstrate advantages of applying high-accuracy physical-optics simulations to the
optimization and performance prediction of X-ray optical beamlines in these new sources.