Dynamic magnetic fields continuously emerging from the solar interior on a wide range of scales, and their interaction with convectively-driven plasma flows, play a major role in shaping the whole solar atmosphere.

Even though the fundamental spatial scales of turbulence and magnetic fields are still unreachable with present-day telescopes, polarimetric observations at the highest possible resolution will allow important insights into these issues. The novel double-interferometer IBIS, developed in Arcetri, will be appropriate for spectro-polarimetric studies at high resolution, both spatial and temporal, using a suitable interface between the polarimeter and the monochromator itself. We will explore the possibilities for extending current IBIS capabilities with a state of the art polarimeter, and perform initial observations in this new mode. We plan for example to attempt observations at high resolution of linear polarization at the limb in the NaD2 589.0 nm line. Such polarization, produced by coherent scattering processes, has great potential for magnetic-field diagnostics through the Hanle effect (Landi degl'Innocenti, 1998; Stenflo et al., 1998; Trujillo Bueno et al., 2002). Small scale, quiet Sun photospheric magnetic structures will also be investigated using the Zeeman effect in the well understood FeI 630.2 nm line. Finally, high resolution polarimetric observations of the CaII 854.2nm line (within the spectral ranges currently available to IBIS), can provide insights into the structure of magnetic fields in the chromosphere, a region where both the geometry of the field and its relevance with respect to convective and turbulent motions change dramatically with respect to the photosphere.

Information on the performances of a high resolution tunable monochromator working in polarized light will be much valuable to assess feasibility of similar instruments that are planned to reside on satellites (e.g, SOLAR-B, to be launched in 2005) or on balloons (Sunrise, to be launched in 2006).