SOPHIA

URI permanente para esta comunidad

https://hdl.handle.net/10784/1122

Tiene como propósito generar y transferir conocimientos, apropiar y desarrollar métodos y tecnologías en las áreas de procesamiento de señales electromagnéticas, dispositivos biofotónicos e instrumentación agroambiental orientados al desarrollo de productos en los ámbitos científico, académico y productivo, nacional e internacional.

Líneas de investigación: Dispositivos biofotónicos, Instrumentación agroambiental, Procesamiento de señales electromagnéticas.
Código Minciencias: COL0011527.
Categoría 2021: A.
Escuela: Ciencias Aplicadas e Ingeniería.
Líder: René Restrepo Gómez
Correo electrónico: rrestre6@eafit.edu.co

Noticias

https://www.eafit.edu.co/sistema-ciencia-tecnologia-innovacion/investigacion/grupos-investigacion/sophia
https://scienti.minciencias.gov.co/gruplac/jsp/visualiza/visualizagr.jsp?nro=00000000008094

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Mostrando 1 - 8 de 8

Contrast inversion in the Lau phenomena implemented with a photorefractive grating
(SPIE, 1999-07-06) Ángel Toro, Luciano; Tebaldi, Myrian Cristina; Bolognini, Néstor Alberto; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
It was implemented the Lau effect with a grating registered in a BSO crystal. Two different arrangement were analyzed. In both cases, it is possible to control the visibility and to produce the contrast inversion of fringes, by properly setting the pass plane orientation of an analyzer located at the crystal output.
Design of a control system for interferometric fringe stabilization system with remote access
(SPIE, 2013-11-18) Espitia-Gómez, Javier; Ángel Toro, Luciano; Velásquez Prieto, Daniel; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
Stability in a fringe pattern is a necessary condition in interferometric processes, such as holography, and not always is enough the use of passive stabilization systems, like holographic tables, in particular, when perturbations are caused by thermal or acoustic variations. For these cases, active systems are required. In this work it is presented the implementation of a control system for interferometric fringes stabilization. The interferometric arrangement characteristics are also discussed, which permits to act independently over each of the interferometer's arms by means of two piezoelectric actuators that change the length of the optical path of light that goes through, in order to perturb the system and simultaneously compensate this perturbation in real time. It is also shown that the proposed system allows evaluating the control system's performance subjected to diverse perturbations, and it is shown how remote access was given to the implemented platform. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Double aperture speckle method using a BSO crystal for in plane displacement
(SPIE, 1999-07-06) Trivi, Marcelo Ricardo; Tebaldi, Myrian Cristina; Bolognini, Néstor Alberto; Ángel Toro, Luciano; Tebaldi, Myrian Cristina; Bolognini, Néstor Alberto; Trivi, Marcelo Ricardo; Ángel Toro, Luciano; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
The possibility of using a BSO crystal as a recording medium of specklegrams with carrying frequency fringes, to storage multiple interferograms, for uniform in-plane displacements, is presented. Experimental results are shown.
Speckle interferometric technique to assess soap films
(Elsevier B.V., 2003-10-17) Ángel Toro, Luciano; Bolognini, Néstor Alberto; Tebaldi, Myrian Cristina; Trivi, Marcelo Ricardo; Universidad EAFIT. Departamento de Ciencias Básicas; langel@eafit.edu.co; Óptica Aplicada
An speckle interferometric technique to monitor the thinning process of vertical soap film before the film rupture is presented -- The interferometric arrangement consists in a double aperture pupil optical system which images an input diffuser -- In a first step, a reference specklegram is stored in the computer buffer memory -- Afterwards, the soap film is located in front of one pupil aperture, an uniform displacement of the diffuser is produced and a new speckle pattern is stored -- The soap film status is characterized in terms of the changes that this dynamic phase object introduces in the correlation fringes obtained by applying a FFT algorithm to the resulting summed specklegram. This procedure is done in real time as far as the soap film evolves in the successive status -- It is experimentally demonstrated that the soap film during drawing acts as a variable wedge -- The correlation fringes behavior becomes an important tool to establish the wedge shaped soap film angle and the thickness variations 2003 Elsevier B.V. All rights reserved
Speckle photography through different multiaperture pupils
(SPIE/ 18th Congress of the International Commission for Optics, 1999-07-19) Ángel Toro, Luciano; Tebaldi, Myrian Cristina; Bolognini, Néstor Alberto; Trivi, Marcelo Ricardo; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
An image multiplexing method based on the internal modulation of speckle grains by employing different multiple aperture pupils for recording is proposed. The interferometric fringes profile and visibility in the Fourier plane, for uniform in-plane displacement double- exposed specklegrams through different pupils recording, are analyzed in terms of the geometric parameters of the pupils. Experimental evidences are presented.
Speckle photography with different pupils in a multiple-exposure scheme
(Optical Society of America, 2000-01-01) Ángel Toro, Luciano; Bolognini, Néstor Alberto; Tebaldi, Myrian Cristina; Trivi, Marcelo Ricardo; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
The use of different multiple-aperture pupils for recording each image in speckle photography is proposed -- The introduction of suitable spatial frequency carriers, by internally modulating imaged speckles, allows one to selectively isolate or combine the spectral content of different images into spatially separated regions in the Fourier plane -- Theoretical and experimental results extend the speckle photography technique to the depiction of several specklegrams of multiple uniform in-plane displacements -- In this case, because different pupils are considered for recording, the cross-correlation functions for the amplitudes and intensities in the image plane are calculated on the basis of the statistical properties of the object -- Also, the ensemble-average intensity in the Fourier plane is analytically derived, and fringe visibility is investigated. © 2000 Optical Society of America [S0740-3232(00)01701-4]OCIS codes: 120.0120, 120.3180, 120.3940, 120.6160
Talbot and Lau phenomena implementation via a photorefractive converter
(SPIE, 1999-07-06) Tebaldi, Myrian Cristina; Ángel Toro, Luciano; Bolognini, Néstor Alberto; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
We propose a novel implementation of the Lau and Talbot effects. It employs a grating registered as modulation of birefringence in a Bi12SiO20 crystal. The systems proposed allow to control the visibility and in particular to reverse the contrast of the self images and Lau fringes by rotating an analyzer. A theoretical approach is outlined and the predicted behavior is confirmed by results obtained under different experimental conditions. We have taken advantage of the arrangements to demonstrate some applications.
Vortex metrology using Fourier analysis techniques: vortex networks correlation fringes
(OSA, 2012-10-19) Ángel Toro, Luciano; Sierra Sosa, Daniel; Tebaldy, Myrian; Bolognini, Néstor; Ángel Toro, Luciano; Sierra Sosa, Daniel; Tebaldy, Myrian; Bolognini, Néstor; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
In this work, we introduce an alternativemethod of analysis in vortexmetrology based on the application of the Fourier optics techniques. The first part of the procedure is conducted as is usual in vortexmetrology for uniformin-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 fromeach recorded intensity pattern by using a version of the Riesz integral transform. Then, fromeach 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 transformas amathematical operation to compute the far-field diffraction intensity pattern corresponding to themultiaperture set. Each aperture fromthe set is associatedwith 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. © 2012 Optical Society of America OCIS codes: 050.4865, 030.6140.

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Examinando SOPHIA por Autor "Ángel Toro, Luciano"

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