The optical vortices arise around zero points of intensity, which lie on the zero-crossing lines of real and imaginary parts of wave field on real-plane. The appearance of the optical vortices is an indication of transition of wave into a new more complex state. Numerous theoretical and experimental papers are devoted to the investigation of such objects; the points are located in the recovery problems of optical wave fields. However, the localization of the real- plane zero points is impossible for experimental data because of discretization and quantization of signals. Therefore an analytical model is necessary to study the creation and the annihilation of the opticla vortex pair and other special points at wave propagation. The wave field in the investigated area is approximated by irreducible second order polynomial of two variable for conservation of local convexity of zero-crossing lines. It has been found analytically and numerically that the local minima of intensity precede the zero, that is complicated point without vortex and which, during wave evolution, bifurcate in two real-plane zero points separated by the saddle point.
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