Digital Talbot interferometer

Based on the self-imaging phenomenon a digital Talbot interferometer is pro posed. This arrangement allows the detection of phase changes introduced by a phase object. The output of the interferometer displays the fringe patte rn obtained through the digital subtraction between two stored intensity di stributions corresponding to a self-image plane where the phase-object is p laced before the second image is captured. Due to the nature of the method a relative rotation of the grating is avoided. The fringe pattern results f rom the spatial beating between the self-image and its modified version int roduced by the phase object. The frequency of the beating is related to the quantitative change introduced by the phase object. To test the performanc e of the interferometer, experimental results where the phase objects are l enses are presented. The experiment gives a good characterization of the te sted objects. A quantitative analysis is conducted through a straight forwa rd model. which is based on the beating between the self-image and its defo rmed version.