Examinando por Autor "Sierra-Sosa, Daniel"
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Ítem Effect of the internal modulation of speckles in displacement measurements in optical vortex metrology(SPIE-INT SOC OPTICAL ENGINEERING, 2013-01-01) Gomez-Tejada, Daniel; Sierra-Sosa, Daniel; Castaneda, Roman; Angel-Toro, Luciano; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThe Optical Vortex Metrology is based on the possibility of characterizing, through topological and morphological parameters, each one of the vortices existing in the phase of the optical field, or in a pseudo-phase obtained by means of the Hibert, Reisz or Laguerre-Gauss transforms. On this basis, it is possible tracking and pairing the homologous vortices. Then, the locations and relative displacements between the homologous vortices are determined with sub-pixel precision. Because of the statistical nature of the measurements, their quality is determined, among other factors, by the amount of available vortices per unit area. In this work, it is proposed to use the internal modulation of the speckles to generate a significant increase in the vortex density, which can be achieved by employing a double aperture pupil optical system. Simulations of the speckle distributions are presented to analyze the increase of the vortex density as a function of the distance between the apertures, and to evaluate the influence of the increment of this density in the quality of uniform in-plane displacements measurements. The results corresponding to modulated speckles are compared with those obtained with a single aperture. © 2013 SPIE.Ítem Effect of the internal modulation of speckles in displacement measurements in optical vortex metrology(SPIE, 2013-11-08) Gómez-Tejada, Daniel; Sierra-Sosa, Daniel; Castañeda, Román; Ángel-Toro, Luciano; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThe Optical Vortex Metrology is based on the possibility of characterizing, through topological and morphological parameters, each one of the vortices existing in the phase of the optical field, or in a pseudo-phase obtained by means of the Hibert, Reisz or Laguerre-Gauss transforms. On this basis, it is possible tracking and pairing the homologous vortices. Then, the locations and relative displacements between the homologous vortices are determined with sub-pixel precision. Because of the statistical nature of the measurements, their quality is determined, among other factors, by the amount of available vortices per unit area. In this work, it is proposed to use the internal modulation of the speckles to generate a significant increase in the vortex density, which can be achieved by employing a double aperture pupil optical system. Simulations of the speckle distributions are presented to analyze the increase of the vortex density as a function of the distance between the apertures, and to evaluate the influence of the increment of this density in the quality of uniform in-plane displacements measurements. The results corresponding to modulated speckles are compared with those obtained with a single aperture. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.Ítem In-plane displacement measurement in vortex metrology(2013-10-09) Angel-Toro, Luciano; Sierra-Sosa, Daniel; Tebaldi, Myrian; Bolognini, Néstor; Angel-Toro, Luciano; Sierra-Sosa, Daniel; Tebaldi, Myrian; Bolognini, Néstor; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaRecently we proposed an alternative method of displacement analysis in vortex metrology, based on the application of the Fourier optics techniques, that is suitable for an intermediate range of displacement measurements ranging below the resolution of speckle photography and above that of the conventional vortex metrology. However, for smaller displacements, we introduce an approach to perform the Fourier analysis from vortex networks. In this work, we present an enhanced method for measuring uniform in-plane displacements, taking advantage of the capability of determining the subpixel locations of vortices and having the ability to track the homologous vortices onto a plane. It is shown that high-quality fringe systems can be synthesized and analyzed to accurately measure in an extended range of displacements and for highly decorrelated speckle patterns. Experimental results supporting the validity of the method are presented and discussed. © 2013 Optical Society of AmericaÍtem In-plane displacement measurement in vortex metrology by synthetic network correlation fringes.(OPTICAL SOC AMER, 2013-03-01) Angel-Toro, Luciano; Sierra-Sosa, Daniel; Tebaldi, Myrian; Bolognini, Nestor; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaRecently we proposed an alternative method of displacement analysis in vortex metrology, based on the application of the Fourier optics techniques, that is suitable for an intermediate range of displacement measurements ranging below the resolution of speckle photography and above that of the conventional vortex metrology. However, for smaller displacements, we introduce an approach to perform the Fourier analysis from vortex networks. In this work, we present an enhanced method for measuring uniform in-plane displacements, taking advantage of the capability of determining the subpixel locations of vortices and having the ability to track the homologous vortices onto a plane. It is shown that high-quality fringe systems can be synthesized and analyzed to accurately measure in an extended range of displacements and for highly decorrelated speckle patterns. Experimental results supporting the validity of the method are presented and discussed.Ítem Novel vortex-transform for high frequency modulated patterns(OPTICAL SOC AMER, 2013-10-07) Sierra-Sosa, Daniel; Angel-Toro, Luciano; Bolognini, Nestor; Tebaldi, Myrian; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaA novel vortex-transform is proposed. This transform allows for generating complex-valued functions from modulated intensity patterns, including high frequency components from modulation, without the generation of unstable phase singularities. From these complex-valued functions it is possible to obtain intensity and pseudo-phase maps to analyze the intensity recordings without the necessity of phase retrieval techniques. The intensity and pseudo-phase maps obtained by using this transform preserve the modulation structure onto the intensity and phase modulo 2? maps, including stable phase singularities. ©2013 Optical Society of America.Ítem Speckle decorrelation influence on measurements quality in vortex metrology(ELSEVIER SCIENCE BV, 2012-10-01) Angel-Toro, Luciano; Sierra-Sosa, Daniel; Tebaldi, Myrian; Bolognini, Nestor; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaWe study speckle decorrelation effects in connection with conventional vortex metrology techniques. Our proposal is based on processing speckled images recorded by using two different experimental set-ups. In both schemes two laterally displaced patterns are generated: one scheme allows for obtaining undecorrelated speckle distributions and the other for decorrelated ones. Vortex networks associated with speckle patterns are analyzed by employing the usual tools developed for vortex metrology. For each recorded image, a 2D pseudo-phase map is generated on the basis of the Reisz transform. Then the vortices are located, and parameterized in terms of their topological charge, eccentricity, vorticity and angles between the zero crossing lines from the real and the imaginary parts of the analytical signal. After tracking the homologous vortices onto the maps, the histograms corresponding to the coordinate displacements are analyzed. We show that histograms interpretation is prone to failure due to its high sensitivity to decorrelation. Experimental evidences are presented to support the restrictions imposed by decorrelation of actual speckles due to uniform in-plane displacements. © 2012 Elsevier B.V. All rights reserved.Ítem Vortex metrology using Fourier analysis techniques: vortex networks correlation fringes.(OPTICAL SOC AMER, 2012-10-20) Angel-Toro, Luciano; Sierra-Sosa, Daniel; Tebaldi, Myrian; Bolognini, Nestor; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaIn this work, we introduce an alternative method of analysis in vortex metrology based on the application of the Fourier optics techniques. The first part of the procedure is conducted as is usual in vortex metrology for uniform in-plane displacement determination. On the basis of two recorded intensity speckled distributions, corresponding to two states of a diffuser coherently illuminated, we numerically generate an analytical signal from each recorded intensity pattern by using a version of the Riesz integral transform. Then, from each analytical signal, a two-dimensional pseudophase map is generated in which the vortices are located and characterized in terms of their topological charges and their core's structural properties. The second part of the procedure allows obtaining Young's interference fringes when Fourier transforming the light passing through a diffracting mask with multiple apertures at the locations of the homologous vortices. In fact, we use the Fourier transform as a mathematical operation to compute the far-field diffraction intensity pattern corresponding to the multiaperture set. Each aperture from the set is associated with a rectangular hole that coincides both in shape and size with a pixel from recorded images. We show that the fringe analysis can be conducted as in speckle photography in an extended range of displacement measurements. Effects related with speckled decorrelation are also considered. Our experimental results agree with those of speckle photography in the range in which both techniques are applicable.