The intermediate scattering function S(q,τ) of a bicontinuous microemulsion is shown in figure 1, where one probes the thermal fluctuations of the surfactant membrane at different q values. The inset shows an echo group obtained in the direct beam at λ = 5 Å and a Fourier time of τ = 0.24 ns. The maximum amplitude of the oscillation compared to the average contains the desired information on the time dependence of S(Q, τ). The residual intensity at the minimum is caused by the imperfection of the polarizes, general background and - rather for higher τ’s - by magnetic path integral in homogeneities.