In this paper, we describe a theoretical model, which allows simulating speckle pattern in an imaging system and its
detection by an image sensor with a limited number of pixels. This simulation tool is based on the Fourier Optics theory.
Preliminary tests show a very good agreement between simulations and experiments. We have demonstrated
experimentally and theoretically that sub-micrometer displacement resolution is possible by means of the crosscorrelation
of speckle patterns, over a range limited to half of the field-of-view of the imaging system.