  High-resolution spectropolarimetry is a useful astronomical technique, in
particular to study stellar magnetic fields. It has been extensively used in
the past but mostly in the visible range. Space missions equipped with
high-resolution spectropolarimeters working in the ultra-violet (UV) are now
being studied. We propose a concept of a polarimeter working with temporal
modulation and allowing to perform Stokes IQUV measurements over the full UV +
Visible range. The purpose of this article is to describe the polarimeter
concept, two prototypes and the bench developed to perform on ground testing to
establish the performances of this new polarimeter.
