Sp ecific features of differential motions in the DIMM V. Kornilov, B. Safonov May 28, 2010 1 Intro duction Differential image motion monitor DIMM widely used in studies of optical turbulence, is destined to measure the integrated effect of the Earth's atmosphere on the image quality. ... In the work of Martin, they are obtained by gradual spatial filtering 1 of the power spectrum of phase perturbations in the assumption of Kolmogorov's model of the optical turbulence (OT). ...