<title>Effect of finite outer scale on the temporal properties of atmospheric tilt aberrations</title>

Abstract

The temporal properties of the tilt aberration induced in a plane wave upon propagation through the atmosphere depends upon the statistical characteristics of the optical turbulence encountered along the propagation path. While the Kolmogorov model with infinite outer scale is often employed to describe turbulence, experimental studies indicate that the effective outer scale of atmospheric turbulence, designated L0, is on the order of 5 m to 100 m. Accounting for the effects of finite outer scale alters the correlative properties of phase aberrations of all orders. Using Taylor's frozen flow hypothesis, we extend the results of spatial correlation studies to model the temporal correlation of wave-front tilt when atmospheric winds are presented. We show that the correlative properties of the wave-front tilt depends upon the quantity v(tau) /D, where v is the wind speed, (tau) is the time delay between tilt measurements, and D is the diameter of the aperture in which the tilt is measured. The outer scale affects the temporal correlation according to the ratio L0/D. Our results demonstrate that the tilt correlation falls off more rapidly as the relative outer scale is decreased. Correspondingly, the tilt power becomes more concentrated at higher frequencies.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.