Effect Of The Atmosphere On Measurement Of Correlations Of Intensity

We consider the effect of turbulence in the atmosphere on measurement of correlations of the intensity of radiation received from an incoherent source. The measurements considered are made on the ground and the source is located well above the turbulent atmosphere. General expressions will be presented which give the two-point correlation of intensities in terms of the source-intensity distribution and the turbulence correlation function. We will give simplified results when isoplanicity is a valid assumption, but will also show a first-order correction to account for non-isoplanicity. Numerical results will be presented for both weak and strong turbulence effects. Finally, we will briefly discuss the three-point correlation function.