The optimum structure for phase incoherent reception in the multipath transmission is discussed in this paper.

Based on the Moire effect in shadow-casting of two coded masks a new kind of optical method is proposed to map phase variation on the object image with an extended incoherent illumination.

The results indicate that the information about phase change of the input object function can be obtained under given conditions, when it is illuminated by an incoherent quasi - monochromatic source.