Evolution behavior of two edge dislocations passing through an astigmatic lens.

The evolution behavior of two edge dislocations passing through an astigmatic lens is studied. It is shown that the edge dislocations are unstable in general. They may vanish or decay into vortices under certain conditions. The appearance, disappearance and motion of phase singularities may take place by varying the off-axis distance of the edge dislocations, the astigmatic coefficient of the lens, the angle between two edge dislocations, and the propagation distance. Vortices or edge dislocations may appear at the geometrical focal plane for two perpendicular edge dislocations, whereas no phase singularities occur for two parallel edge dislocations. [ABSTRACT FROM AUTHOR]