Aladdin Nulling Instrument

The ALADDIN project aims at detecting warm dust populations around nearby main sequence stars. In order to achieve the significantly improved sensitivity with respect to existing instruments, the architecture of the system is focused and optimised for the mission: ALADDIN implements the nulling interferometry technique at the focal plane of a 2-telescope interferometer mounted on a rotating structural beam. Concerning the beam combining nulling instrument, the ALADDIN design is inherited from a Definition Study of the VLTI/GENIE instrument, performed a few years ago by an industrial consortium for the European Space Agency and the European Southern Observatory. In this paper, we demonstrate how the ALADDIN instrument preliminary definition can be made simpler and more representative of a space instrument than GENIE thanks to both the outstanding atmospheric properties of Dome C and the dedicated architecture of the system. In particular, real-time controls of the chromatic dispersion of the phase and intensity matching can be discarded, while the remaining control of the phase is substantially relaxed. Furthermore long-stroke delay lines and dispersion correction hardware can be removed from the optical table. Finally, we discuss the compatibility of the instrument with the Antarctic environment and constraints, and underline the experimental and industrial know-how learnt from the MAII and PERSEE nulling breadboards in which our Team is also involved.