The effects of turbulence on the performance of imagers or on beam forming optical systems are well expressed by the optical transfer function (OTF) or its magnitude, the modulation transfer function (MTF). It has been shown that the MTF can be expressed in terms of the Fried model by means of a single number, the turbulence structure constants for optical index, C(2)(n). provided that a properly path weighted value is obtained. Based on current theory the weighting needed in the path-position weighted value of C(2)(n) is a function of (z/x(o))(5/3), heavily emphasizing the region near the imaging system or beam forming optics. It is the conclusion of this report, that the path weighting function (Z/Z(o))(5/3) is correct.

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http://archive.org/details/weightingformodu1094520035

Lieutenant Commander, United States Navy