Optical systems that combine high-power lasers with large-aperture bean directors have been developed as prototypes for a number of tactical defensive weapon systems, and have been proposed for large-scale strategic defense systems. Several such systems are currently in use for propagation measurements and for long-range high-resolution imaging radar applications. For efficient operation, advanced systems use adaptive optics techniques to control the wave front phase distribution . The controller measures and corrects the wave front irregularities introduced by the laser device and internal optical train imperfections between the laser and the exit aperture of the bean director The controller must also provide corrections for the unavoidable aberrations in the external propagation path caused by nature. Atmospheric turbulence and the lending (or thermal blooming) caused by absorption of the transmitted beam in the atmosphere While the controller is designed to correct wave front distortions in practice thermal turbulence created by heated laser optics can overwhelm the ability of the controller to correct the external disturbances .Optical distortion created by uncontrolled air temperature gradients is a problem that is not confined to high-power laser systems. The mirrors and supporting structure in astronomical telescopes typically cool more slowly than the nighttime air. The resulting temperature offsets create thermal turbulence, or mirror currents, that can seriously degrade performance . One solution commonly used by astronomers is to open the dome and let the ambient winds carry the thermal currents out of the beam path.