The achievement of minimal angular divergence of a laser beam is one of the most impor‐ tant problems in laser physics since many laser applications demand extreme concentration of radiation. Under the beam formation in the laser oscillator or amplifier with optically in‐ homogeneous gain medium and optical elements, the divergence usually exceeds the dif‐ fraction limit, and the phase surface of the laser beam differs from the plane surface. However, even if one succeeds in realizing the close-to-plane radiation wavefront at the la‐ ser output, the laser radiation experiences increasing phase disturbances under the propaga‐ tion of the beam in an environment with optical inhomogeneities (atmosphere). These disturbances appear with the wavefront receiving smooth, regular distortions, the trans‐ verse intensity distribution becomes inhomogeneous, and the beam broadens out.