Fast Solar Polarimeter: Prototype characterization and first results

Due to the differential and non-simultaneous nature of polarization measurements, seeing induced crosstalks and seeing limited spatial resolution can easily counterbalance the benefits of ground based Solar imaging polarimetry. It is known that fast modulation in combination with high frame rate can help with these issues. In his line, we are developing the Fast Solar Polarimeter (FSP). FSP prototype is based on a high frame-rate (400 fps), low-noise (< 3 e- RMS), pnCCD camera, and ferroelectric liquid crystals. The fast polarization modulation, yielding up to 100 full-Stokes measurements per second, and high duty cycle (~ 95%), have the double propose of reducing seeing induced artifacts and improving the final spatial resolution by providing an optimal regime for the application of post-facto image reconstruction techniques. In this work we describe the FSP prototype and present some of the first measurements obtained with the 68-cm, Vacuum Tower Telescope located in the Observatorio el Teide, Spain.