IFTSUV: an imaging Fourier Transform Spectrometer in UV for the next solar space missions

The study of the Sun in the UV spectral domain is essential to a better understanding of the physical processes taking place in the solar atmosphere, the temperature of which can reach more than a million Kelvin. The main tools available are solar disk and corona imagers and spectrometers. Nevertheless, the analysis of imagery data is rapidly limited unless spectral information is given and the association of spectrometers and imagers is limited by the lack of the coherence between the instruments. Therefore, the design of an imaging spectrometer in UV is a priority for solar physicists. A Fourier transform spectrometer is the ideal candidate because of its spectral resolution (theoretically unlimited) and its capability of imaging a wide field. An optical concept has been studied and a mock-up has been built, aligned and tested in order to validate the working principle. This mock-up helped us identifying difficulties associated with the building of such an instrument, difficulties specific to working in the UV domain. A prototype will be built based on the mock-up and is intended to be accommodated on a solar observation satellite by 2015.