MUTUAL COHERENCE FUNCTION DETERMINATION FROM A DOUBLE POINT-SOURCE PROPAGATING THROUGH A TRANSVERSELY AND LONGITUDINALLY INHOMOGENEOUS AERO-OPTIC TURBULENCE LAYER

The mutual coherence function (MCF) that results when a double point s ource illuminates a transversely and longitudinally inhomogeneous turb ulence layer is considered. The analysis was carried out by (1) decomp osition of the free-space MCF from the double point source into four s eparate interference terms, (2) calculation of the MCF that resulted f rom each of these terms when the optical wave that arose from these te rms propagated through the inhomogeneous turbulence layer, and (3) add ition of the solutions together to form the overall MCF solution of th e optical system. The analysis was carried out in a transverse center- difference coordinate system. Two of the four terms were shown to vary rapidly in the center coordinate variables, and the other two were sh own to vary rapidly in the difference coordinate variables. Because tw o of the terms showed rapid interference effects in the center coordin ate variable and the other two in the difference coordinate variable, two different spatial-spectral algorithms were developed in the paper to analyze the MCF's that arose from each of the two types of rapid in terference variation. The spatial-spectral MCF equations that arose fr om the analysis were solved numerically by the Lax-Wendroff finite-dif ference method. Several numerical plots of the center and difference i nterference MCF's that resulted when a double point source was inciden t upon a transversely inhomogeneous aero-optic layer were given. Plots of the variation of the interference MCF's with angular separation of the double point source are shown.