title: Stable deep nulling in polychromatic unpolarized light with multiaxial beam combination.
abstract: In the context of the space-based nulling mission ESA-Darwin, Thales Alenia Space has developed a nulling breadboard for the European Space Agency (ESA): the multiaperture imaging interferometer (MAII) to demonstrate deep and stable nulling and to investigate various subsystems of the ESA-Darwin interferometer. Recently, we have extended our investigations to the multiaxial beam combination. This combination scheme presents many advantages: simplicity, compactness, and a high coupling efficiency for a three-beam combination. The near-infrared (lambda approximately 1.55 microm) MAII breadboard has been upgraded to the multiaxial beam combination. Polarization and stability issues have been thoroughly investigated. We report on the recent results we have obtained with the multiaxial configuration of MAII in unpolarized light with a relative spectral bandwidth of 5%: nulling ratios of mean value N=1.7 x 10(-5), stable over 1 h with a standard deviation sigma( N )=5.7 x 10(-7). These results indicate that the multiaxial beam combination has the potential to meet Darwin requirements.
authors.affiliation: Département Gemini, Observatoire de la Côte d'Azur, UMR CNRS 6203, Avenue Copernic, 06130 Grasse, France. christophe.buisset@obs-azur.fr
authors.forename: Christophe
authors.initials: C
authors.lastname: Buisset
authors.forename: Xavier
authors.initials: X
authors.lastname: Rejeaunier
authors.forename: Yves
authors.initials: Y
authors.lastname: Rabbia
authors.forename: Marc
authors.initials: M
authors.lastname: Barillot