Results of the High Resolution OTR Measurements at KEK and comparison with simulations

Optical Transition Radiation (OTR) is emitted when a charged particle crosses the interface between two media with different dielectric properties. It has become a standard tool for beam imaging and transverse beam size measurements. At the KEK Accelerator Test Facility 2 (ATF2), OTR is used at the beginning of the final focus system to measure micrometre beam size using the visibility of the OTR Point Spread Function (PSF). In order to study in detail the PSF and improve the resolution of the monitor, a novel simulation tool has been developed. Based on the physical optic propagation mode of ZEMAX, the propagation of the OTR electric field can be simulated very precisely up to the image plane, taking into account aberrations and diffraction. This contribution presents the comparison between Zemax simulations and measurements performed at ATF2.