Abstract

Kolmogorov turbulence theory predicts an inertial range of turbulence where the power spectrum for refractive-index fluctuations follows a 5/3 power law. In theoretical studies the large-scale limit of the inertial range is often taken to be infinite, although this is a nonphysical assumption. In recent years a number of measurements of the outer scale have been reported, usually of the order of 5–10 m, but none is directly applicable to propagation studies. There are currently several projects to develop 8-m class telescopes, and it seems that for these large scale optical systems the effect of the outer scale may become significant. The Zernike decomposition of atmospheric optical turbulence is derived for the case of a Kolmogorov spectrum modified by the presence of a finite outer scale. The results indicate significant attenuation of tilt and low-order aberrations on medium to large telescopes if the path-integrated effective outer scale is of the order of 5–10 m. The sensitivity of an experimental technique for direct measurement of the outer scale is calculated.

© 1988 Optical Society of America