Effect of spatial coherence on laser space-debris removal in the inhomogeneous atmosphere

Abstract

We derive the analytical formulae of the beam width, the spatial coherence width and the curvature radius of partially coherent beams (PCBs) propagating from the ground through the atmosphere to the orbital debris. The focal shift takes place because of beam diffraction and Kerr nonlinearity effects. It is found that the actual focus can be moved to the debris target by initial beam defocusing only when the initial spatial coherence width is larger than a critical value. We derive the analytical formula of the modified focal length Fmod of the lens to move the actual focus of PCBs to the debris target. The Fmod increases as the initial spatial coherence width decreases. It is demonstrated that the detrimental diffraction and Kerr nonlinearity effects can be compensated effectively only when the Fmod is less than a maximum.