CONTROL OF WAVE-FRONT PROPAGATION WITH DIFFRACTIVE ELEMENTS

In principle, diffractive elements can be designed to control a propag ating wave in three dimensions, but no general procedure has been prop osed. We present an iterative method that is suitable for the design o f such diffractive elements. The resulting complex amplitude distribut ion will approach any arbitrary requirement, as much as is permitted b y basic physical principles. The problem of ''nondiffracting-beam'' pr opagation is analyzed as a special case, and intensity peaks are gener ated that propagate as much as 4 m with a bounded width. The generalit y of the method, as compared with other techniques, is demonstrated by the design of an array of nondiffracting beams.