Imaging of optical diffraction radiation in pre-wave zone and spatial resolution of non-invasive beam size diagnostics

A simple model to evaluate the imaging shape of an optical diffraction radiation (ODR) source focused by a lens on a detector, taking into account the pre-wave zone effect has been developed. The characteristic size of an ODR image does not depend on the Lorentz-factor and is defined by the impact-parameter (minimal distance between a particle trajectory and ODR target edge) only. Using the ODR intensity component polarized parallel to the target edge it is possible to significantly improve the spatial resolution of an ODR beam profile monitor.