Incoherent superimposition of multiple self-imaging under plane wave-front illumination

Characteristics of the diffraction field of two spatially separated linear diffraction gratings under incoherent illumination are studied. In contrast to the previous studies concerning the so-called Lau effect the grating separation distance is assumed to be infinitely large. The analytical model is based on the superimposition theory of mutually incoherent Talbot effects. It gives a simple explanation of the basic parameters of the diffraction images for prediction and discussion of the performance of grating shearing interferometers using a periodic, spatially extended light source. The experimental verification of theoretical analyses is given.