Design, Construction and Field Characterization of A Variable Polarization Undulator for SOLEIL

Two variable polarization undulators have been designed and are under construction in the framework of a Collaboration agreement between Société Civile Synchrotron SOLEIL and Sincrotrone Trieste. In this paper the main aspects of the magnetic and mechanical design are summarized. Field optimization techniques are described, showing the achieved performance in terms of phase, trajectory and field integral errors.