Aperture averaging and the temporal spectrum of optical scintillations

By using a recently developed theory of scintillation that is valid under fluctuation conditions that include the focusing and saturation regimes, we develop a general model for predicting power fluctuations (or aperture averaging) over a finite-size collecting aperture. In addition, we calculate the covariance function and implied temporal spectrum of such power fluctuations. Increasing the size of the collecting aperture decreases the high frequency content of the irradiance spectrum.