Automatic focusing in digital holography and its application to stretched holograms

Year: 2011

Authors: Memmolo P., Distante C., Paturzo M., Finizio A., Ferraro P., Javidi B.

Autors Affiliation: CNR-Istituto Nazionale di Ottica, via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy; DIBET, Università degli Studi di Napoli “Federico II”, via Claudio 21, 80125 Napoli, Italy; CNR-Istituto Nazionale di Ottica, viale della Libertà 3, 73010 Arnesano (LE), Italy; Electrical and Computer Engineering Department, University of Connecticut, U-2157 Storrs, Connecticut 06269-2157, USA

Abstract: The searching and recovering of the correct reconstruction distance in digital holography (DH) can be a cumbersome and subjective procedure. Here we report on an algorithm for automatically estimating the in-focus image and recovering the correct reconstruction distance for speckle holograms. We have tested the approach in determining the reconstruction distances of stretched digital holograms. Stretching a hologram with a variable elongation parameter makes it possible to change the in-focus distance of the reconstructed image. In this way, the proposed algorithm can be verified at different distances by dispensing the recording of different holograms. Experimental results are shown with the aim of demonstrating the usefulness of the proposed method, and a comparative analysis has been performed with respect to other existing algorithms developed for DH. (C) 2011 Optical Society of America

Journal/Review: OPTICS LETTERS

Volume: 36 (10)      Pages from: 1945  to: 1947

KeyWords: Optical-scanning Holography; Fresnel Holograms; Microscopy; Objects; Depth; Autofocus
DOI: 10.1364/OL.36.001945

Citations: 181
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