Structure function and PSD of the n_φ=10000 simulated turbulent phase screens normalised by . Panel a: average radial profiles of the 2D structure function: Theoretical profile (D_φ(x); black), profile of the simulated set computed in the direct space ; green) and theoretical profile computed in the frequency domain ; blue). Panel b: theoretical 2D map of the PSD Φ_φ(k). The grey square represents the cut-off frequency |k_i∊{1,2}| < (2Δ)⁻¹.