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 techniqu e, electronic speckle-pattern interferometry, differential interferometry, digital holography and holographic interferometry with a photorefractive cr ystal. The sharing of most of the optical lenses allows a compactness of ha rdware compatible with space-application requirements (the Fluid Science La boratory for the International Space Station). Performances and complementa rity of techniques are discussed. Interferometric methods for refractive-in dex measurement are compared and preliminary experimental results are given .