Simulating phase screens

The simulation and performance evaluation of high-order, adaptive-optics (AO) corrective systems for the new, large telescopes require the generation of distorted wavefronts (WF) that accurately model the behavior of the real atmosphere. Roggemann et al. (1) have introduced a method of accurately generating distorted wavefronts based on the covariance matrix of wavefront distortions and Cholesky factorization. Several authors have proposed fractional-Brownian-motion algorithms that are more computationally efficient as alternatives for generating distorted wavefronts but do not give accurate correlations. In this paper, the fractional Gaussian process (FGP) algorithm is introduced as a new method of generating distorted wavefronts. The algorithm is presented in both one and two dimensions. The correlation function and power spectra of simulated wavefronts are shown to compare well to the expected correlation and power spectra respectively. It is concluded that the FGP algorithm is an accurate and efficient method of generating simulated wavefronts.