Grating pseudo-imaging with polychromatic and finite extension sources

The pseudo-imaging process in a system consisting of two periodic gratings and illuminated by an incoherent polychromatic and finite extension source placed at a finite distance from the gratings is studied. An analytical expression of the irradiance distribution on a plane, also located at a finite distance from the gratings, has been obtained from previous results on monochromatic illumination. In the analysis presented, different imaging regimes are found and related to the parameters which characterize the double grating system. The pseudo-imaging phenomenon strongly depends on both the spatial and temporal coherence of the incident illuminating field. Certain pseudo-images are observed with polychromatic and incoherent incident light under some restrictions. On the other hand, pseudo-image process analogous to Talbot effect appears only by monochromatic and plane illuminating wavefront. (C) 2004 Optical Society of America.