Dynamic image analysis for dynamic scattering modes in a nematic liquid crystal

We have investigated the pattern fluctuation in a highly developed electro- hydrodynamic convection (EHC) by dynamic analyses of spatial Fourier coeffi cients of images. We measured the power spectrum and the two-time correlati on function of spatial Fourier coefficients of images in the two turbulent states of EHC: the dynamic scattering mode (DSM)1 and DSM2 states. It was f ound that in the DSM1 state both the power spectrum and the correlation tim e show spatial anisotropy and have a characteristic peak at a male number c orresponding to the thickness of the cell in the rubbing direction. The pea ks of the power spectrum and the correlation lime decrease as the applied e lectric field is raised, and vanish entirely when the system undergoes the transition from DSM1 to DSM2. In the DSM2 state, there is no anisotropy in both the power spectrum and the correlation time.