Measurement of a Non-Kolmogorov Structure Function

Abstract

The structure function of atmospheric phase fluctuations is defined as follows: A generalised model for the structure function of phase is: ℛ 0 is related to the size of the long-exposure image formed by a large-aperture telescope, while γ ß is a parameter which depends on ß and on the precise definition of ℛ 0 The widely-used Kolmogorov model of refractive index fluctuations [1] predicts a value of 11/3 for ß; in this case, with the appropriate definition, ℛ0 is equivalent to r0, the Fried parameter [2], Under the Kolmogorov assumption, the parameter r0 entirely describes the time-averaged statistics of the phase fluctuations. A knowledge of r0 can be used, for example, to predict how the energy in the phase fluctuations is distributed between the Zernike modes.