PERSEE: description of a new concept for nulling interferometry recombination and OPD measurement

Abstract

Nulling interferometry requires, among other things, a symmetric recombination module and an optical path difference control system. The symmetric recombination stage has been particularly studied over the last ten years and several concepts are now well known. One of them is the "Modified Mach Zehnder" (MMZ) interferometer, proposed by Serabyn and Colavita (2001) [1]. In this paper, we describe a new version of the MMZ beam combiner which provides a deep null signal in the science channel and, at the same time, phase-sensitive signals in the so-called co-phasing channel. From the latter, accurate optical path difference measurements can be derived. This beam combiner works in the 0.8 to 3.3 μm spectral range (0.8 to 1.5 μm for the co-phasing channel and 1.65 to 3.3 μm for the science channel). Both optical functions can be implemented in the same device thanks to an original optical design involving dedicated phase shifts. In this paper, we describe its principle and detail the optical and mechanical design.