ABSTRACT
In the classical electrodynamics, the theory describes electromagnetic radiation as a flow of time-varying electric and magnetic fields traveling through free space or through a material medium with a universally fixed speed. These fields propagate in a form of harmonic (sinusoidal) electromagnetic waves, characterizing by its intensity, frequency, and polarization. In particular, the Zernike polynomials provide significant correction of turbulent-corrupted wave front in optical imagery. Zernike polynomials and modes are also useful in adaptive optics and laser beam propagation theory. Extended Huygens–Fresnel principle is a popular technique used in analytical studying optical beam propagation in turbulence. This method considers the turbulence as a phase distortion of the spherical wave in the standard Huygens–Fresnel principle, which is well known from the theory of diffraction. The theory of optical scintillation is based on the second-order and fourth-order field moments known, respectively, as the mutual coherence function and fourth-order cross-coherence function.
