Minute details detection through Fresnel diffraction domain Jorge Garcia-Sucerquia a,b, * , Francisco F. Medina c , John Fredy Barrera c a Department of Physics, Dalhousie University, Halifax, NS, Canada B3H 3J5 b Physics School Universidad Nacional de Colombia Sede Medellı ´n, A.A. 3840, Medellı ´n, Colombia c Physics Institute, Universidad de Antioquia, A.A. 1226 Medellı ´n, Colombia Received 31 January 2005; received in revised form 29 April 2005; accepted 1 May 2005 Abstract The capability of distinguishing fine details or perturbations in simple structures by means of Fresnel-domain dif- fraction is shown. Through numerical calculations it is shown that the greater the number of Fresnel zones considered in the diffraction setup the larger differentiability is reached. To illustrate our proposal the case of a circular clear aper- ture in an opaque screen with fine details of variable dimensions and subtending different number of Fresnel zones is studied. It is shown that by taking advantage of the Fresnel-domain diffraction it is possible to distinguish details or defects with area larger than or equal to 1% of the initial structure area, without any kind of mechanical contact between the diffracting structure and the recording media. Ó 2005 Elsevier B.V. All rights reserved. PACS: 42.25.F Keywords: Diffraction; Fresnel domain diffraction 1. Introduction Since the invention of FresnelÕs algorithm to understand the diffraction of optical fields through a circular aperture, it has played an important role in optics [1]. Outstanding experiments and techno- logical developments have been understood and carried out due to the insight added by Fresnel to the optical sciences; for instance, let us recall the AragoÕs experiment. One issue of extensive study in this direction is the delimitation of the Fresnel and Fraunhofer diffraction domains [2]. The determination of the Fresnel–Fraunhofer limit on the diffraction process for all states of coherence has been a topic of study since many years ago until today [3]. Particularly, the under- standing of the diffraction process has been 0030-4018/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.optcom.2005.05.004 * Corresponding author. Tel.: +574 430 9327; fax: +574 260 4489. E-mail address: jigarcia@unalmed.edu.co (J. Garcia-Sucer- quia). Optics Communications 253 (2005) 250–256 www.elsevier.com/locate/optcom