Interferometer for fluid physics experiments in microgravity environment

Several optical instruments are devoted for diagnostic in physico-chemical experiments, performed in microgravity environment. The aim of this paper is to describe a Wollaston interferometer devoted to measure the refraction index gradient of a transparent liquid media, in order to measure the concentration or temperature gradients around a formed drop. The Wollaston interferometer has been chosen because its sensitivity to the wavefront error can be tuned choosing the shearing component. Moreover this interferometer type has been chosen for his compactness and low sensitivity to the vibrations. This interferometer has been developed for the INEX MAM 3-Welcome project (EADS Space, Bremen / ESA contract), in which two different experiments, one devoted to the execution of the Marangoni migration, the other to the Wetting and Coalescence Prevention, have been carried out during the fly of MAXUS 5 Sounding Rocket.