Influence of partially coherent illunination on the moiré process

We present a theoretical analysis of miore fringes formation with partially coherent light. This analysis is based on the propagation laws of the mutual coherence function. Γ. With perfectly coherent light (i.e. laser light) the fringe visibility is maximum only in the Fourier planes. We show the existence of « critical coherence » field srtuctures which reduce the fringe visibility even in he Fourier planes. This analysis shows that periodic object image formation is strongly influenced by the coherence strucure of the light field.