The goal of this experiment is to image SF6 that is input into a vacuum from high pressure through a small nozzle. Interest is given to the dynamics of the bulk particle trajectories and distribution of velocities within the expansion plume. Imaging is accomplished via interferometry, where the measure of the fringe rate can be correlated to the gas density and pressure, ultimately revealing the velocity of the imaging location. Here we present the apparatus and discuss the measurements to be made.