Forming a localized beacon on a non-cooperative extended target through turbulent atmosphere

摘要

Practical implementation of the adaptive optic technique to mitigate the negative effects of the atmospheric turbulence on the propagating laser beam requires a minimal size (point-wise) beacon on the target. Existing methods to address this challenging problem apply sequential iteration cycles and wavefront control with adaptive optics mirror. However a large number of iteration cycles may require a time substantially longer than the frozen time of the atmosphere, especially in presence of the aero-optic effects.This report examines an alternative solution to this problem. Generation of the laser hot spot on the image-resolved diffused target can be achieved by using a phase conjugation scheme and realization of an open cavity with the target serving as one of its couplers. We have demonstrated that controlling the beam structure in the target image plane of the laser transmitter enables formation of the localized beacon on the target. As a result, the number of iterations required for an effective system operation can be significantly reduced, making its operation cycle much shorter than frozen time.