<title>Some current views on singular optics</title>

Abstract

Singular optics has been recognized as separate important branch of modern physics about 15 years ago. Actually, along this period it was developed as <i>coherent</i> singular optics. Fundamental properties of phase singularities and the most important regularities governing the formation of singular skeletons of the field (such as sign principles) have been established both for scalar (uniformly polarized) and for vector (spatially non-uniformly polarized) monochromatic optical fields. Development of coherent singular optics continues. The most interesting and promising event of the last years, especially since 2002, consists in the tendency to expand the singular optical principles on the field of partially coherent light fields. In this context, physically new singular optical concepts are derived, new experimental instrumentation is developed, and new promising applications of the singular optical approaches are elucidated. Analysis of last achievements in the field of singular optics leads to the conclusion on coming into being of new branch of this area of investigation, which can be referred to as the <i>correlation</i> singular optics. It is remarkable that fruitfulness of this new R&amp;D direction is essentially determined by the concepts and results of classical wave optics, which were developed irrespective of the singular optical paradigm.