The UV FTS is an ambitious instrument, however we feel confident that it is technically achievable. We propose an instrument that works in the 170 - 350 nm range. This is dictated by the optical properties of fused silica needed as a substrate for the beamsplitter. UV FTSs are commercially available in this wavelength range (e.g. Chelsea Instruments FT500) and are thus a proven concept.
We would however, very much like to extend the wavelength range below 170 nm to the CIV lines at 154.8 and 155.0. The push to shorter wavelengths drives two major design criteria: mechanical stability and optical wavefront distortions have to be controlled to proportionally better tolerance, and we have to abandon spectrosil as a beamsplitter substrate. This problem is potentially harder to solve, as it will require the adoption of either a reflective grating beamsplitter or a MgF substrate. On the latter, good progress is being made at Imperial College, and they have an experimental interferometer working near the CIV lines.
Obviously if we are to use an extended range FTS extensive studies must be carried out, and the ESA study of SIMURIS would provide a good starting point.