UNFOLDING OF HIGHER-ORDER WAVE DISLOCATIONS

Wave dislocation reactions, for example, one dislocation splitting int o three, are organized by dislocations of higher order. A reaction can be regarded as an unfolding of a higher-order dislocation, rather as singularities in catastrophe theory unfold into clusters of lower-orde r ones. The paper lists the forms of the first few higher-order wave d islocations. It shows how the reaction reported by Karman et nl. [Opt. Lett. 22, 1503 (1997)], in which an Airy dark ring surrounding a focu s splits into three, followed by the annihilation of an inner fourth r ing by the central ring, is part of the unfolding of a fourth-order di slocation. (C) 1998 Optical Society of America.