Simultaneous imaging of periodic object planes

When a zone plate is inserted in the frequency plane of an ordinary 4- f coherent optical processor, self-images are observed at the end of the system. From symmetry considerations we may expect that the same system would image periodic object planes into a single image plane. In this paper we discuss both phenomena assuming incoherent illumination. In the last instance, most of our discussion is oriented to explain the simultaneous imaging of periodic object planes. Experimental results are presented to illustrate both phenomena.