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Proceedings Paper

Concentration limit for mono-disperse colloids observable with numerical DIHM
Author(s): John F. Restrepo; J. Garcia-Sucerquia
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Paper Abstract

Digital In-line Holographic Microscopy (DIHM) is a two-steps microscopy technique that allows for accessing to complex wave information of the optical field scattered by a sample. Initially, the sample is illuminated by a spherical wavefront such that the amplitude superposition of the portions of the spherical wavefront scattered and not by sample, is recorded on a digital camera; the recorded intensity is often referred as in-line hologram. On the second step, a numerical diffraction scheme is used to emulate the diffraction of a spherical wavefront by the in-line hologram therefore producing a reconstruction in amplitude and phase of the original object. Due to its evident experimental simplicity, DIHM is a widely used technique for in-situ applications and more recently on real time measurements. This widespread employment of the technique introduces the necessity of establishing the practical limits achievable with this imaging technique. Particularly, for the practical study of mono-disperse colloids, the critical concentration is a relevant factor to identify, in order to establish the optimal conditions up to which DIHM can successfully work. The reconstruction step produces a set of intensity images, at different axial distances, containing the information of all the recorded particles; in large study volumes and high concentrations the number of particles overcome the easiness of manual processing and therefore evidences the need of implementing more automatic tracking algorithms. In this way the limits of applicability of DIHM rely on both the experimental configuration and the digital processing. With the use of a modeling tool for DIHM and a semi-automatic tracking algorithm, a numerical estimation of the concentration limit for which DIHM can work is proposed, following the analysis for its dependence with the experimental configuration of the recording process.

Paper Details

Date Published: 2 November 2011
PDF: 8 pages
Proc. SPIE 8011, 22nd Congress of the International Commission for Optics: Light for the Development of the World, 80111E (2 November 2011); doi: 10.1117/12.903033
Show Author Affiliations
John F. Restrepo, Univ. Nacional de Colombia Sede Medellín (Colombia)
J. Garcia-Sucerquia, Univ. Nacional de Colombia Sede Medellín (Colombia)

Published in SPIE Proceedings Vol. 8011:
22nd Congress of the International Commission for Optics: Light for the Development of the World
Ramón Rodríguez-Vera; Ramón Rodríguez-Vera; Ramón Rodríguez-Vera; Rufino Díaz-Uribe; Rufino Díaz-Uribe; Rufino Díaz-Uribe, Editor(s)

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