title: Digital phase contrast with the fractional Fourier transform.
abstract: A new method of digital phase contrast based on fractional-order Fourier reconstruction is proposed. We show that the diffraction patterns produced by pure phase objects exhibit linear chirp functions that can be advantageously processed using the fractional Fourier transform. The optimal fractional orders lead to the longitudinal location of the phase object, while the analysis of the reconstructed pattern leads to its diameter and to the value of the phase shift. Simulations and experimental results are given. The configuration tested in this paper is a very general Gaussian illumination.
authors.affiliation: CORIA UMR 6614, Université de Rouen, Avenue de l'université BP 12, 76801 Saint Etienne du Rouvray Cedex, France. marc.brunel@coria.fr
authors.forename: Marc
authors.initials: M
authors.lastname: Brunel
authors.forename: Sebastien
authors.initials: S
authors.lastname: Coëtmellec
authors.forename: Denis
authors.initials: D
authors.lastname: Lebrun
authors.forename: Kamel Aït
authors.initials: KA
authors.lastname: Ameur