This mechanism is the core of the instrument and constitutes a major innovation in the interferometry domain.
Indeed, it makes it possible in only one movement to accomplish the path difference required by the signal analysis and the compensation of the self-apodization function in the field. The combined movement is achieved by linking the two internal prisms and the two external prisms on two pendulums operated by the same motor. The ratio of the lever arms of the two pendulums is computed in order to supply the desired ratio between the path difference and the variation in thickness of the glass needed for the field compensation. Compared to the Mertz principle, it uses only one mechanism, thus eliminating any need for synchronization.
This innovative concept has been jointly patented by Airbus DS and CNES.