Autorreconfiguração de um campo de “speckle”: teoria, experimento e aplicações

Abstract

In this doctoral thesis we explored, through various experiments and theoretical approaches, the ability that a "speckle" field has to recover its cross-section intensity after crossing by an opaque obstacle. To this ability we call self-reconfiguration property. We investigated this effect by observing from the influence of the spatial coherence length on the reconfiguration distance, to possible applications involving image transmission. We start the thesis presenting the phenomenon of "speckle" and then show how its field can self-reconfigure after crossing obstacles. Continuing, we discuss the influence of the spatial coherence length of the "speckles" in the reconfiguration distance of the pattern. We found that this distance is linearly dependent on the coherence length and the obstruction size. Further, we show that it is possible to recover an image embedded in a "speckle" field, after it crosses obstacles. We use the parameters of visibility and similarity to evaluate the recovered image. In the sequence we have studied the robustness of a coherence vortex. We use the self-reconfiguration property of the "speckles" and found that a coherence vortex can preserve its phase after crossing obstacles, proving the unexpected robustness of the coherence vortices. Continuing the studies of the coherence vortex, we show that the cross-section area of such vortex has linear dependence with their effective topological charge. We found that, within a specific setting, you can determine the effective topological charge of a coherence vortex from the knowledge of the area of its cross-section.