The power spectrum of the difference angle of arrival of two parallel rays through turbulent air is computed and the results compared to data and to earlier theoretical work on the subject. The present theory predicts an ƒ<sup>-⅔</sup> power law in the inertial subrange, and thus differs significantly from Tatarski’s, which predicts an ƒ<sup>-⅜</sup> power law. Nevertheless, it fits the existing data in the ƒ<sup>-⅔</sup> region common to both theories. The interferometer situation introduces a filter factor that is unimportant for most vertical interferometers in turbulent air, except at very low frequencies.
D. A. de Wolf, "Angle-of-arrival difference spectrum of a simple interferometer in turbulent air," J. Opt. Soc. Am. 63, 657-660 (1973)