An integrated optical set-up for fluid-physics experiments under microgravity conditions

An integrated optical set-up for fluid-physics diagnostics is proposed. The combined diagnostic tools are direct visualization, the schlieren technique, electronic speckle-pattern interferometry, differential interferometry, digital holography and holographic interferometry with a photorefractive crystal. The sharing of most of the optical lenses allows a compactness of hardware compatible with space-application requirements (the Fluid Science Laboratory for the International Space Station). Performances and complementarity of techniques are discussed. Interferometric methods for refractive-index measurement are compared and preliminary experimental results are given.