Implementation of fast-Fourier-transform-based simulations of extra-large atmospheric phase and scintillation screens

Fast-Fourier-transform-based simulations of single-layer atmospheric von Karman phase screens and Kolmogorov scintillation screens up to hundreds of meters in size were implemented and tested for applications with percent range accuracy. The tests included the expected and the observed structure and pupil variance functions; for the phase, the tests also included the Fried turbulence parameter r(0) measured by the seeing and by a simulated differential image motion monitor. The standard compensations used to correct the undersampling at low spatial frequencies were improved, and those needed for the high spatial frequencies were determined analytically. The limiting ratios of the screen sampling step to r(0) and of the screen size to the pupil aperture were estimated by means of the simulated data. Sample results are shown that demonstrate the performances of the simulations for single-layer Kolmogorov and von Karman phase screens up to 200 m in size and for Kolmogorov scintillation screens for pupils up to 50 m of aperture. (C) 2004 Optical Society of America.