Optica Aplicada

URI permanente para esta comunidad

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

Genera y transfiere conocimiento y apropia métodos y tecnologías en las áreas de procesamiento óptico de información y metrología óptica, relevantes para el avance científico, académico y productivo.

Líneas de investigación: Holografía; Metrología Óptica.
Código Minciencias: COL0011527.
Categoría 2019: A.
Escuela: Ciencias.
Departamento académico: Ciencias Físicas.
Coordinador: Elena Montilla; Carlos Andrés Trujillo.
Correo electrónico: emontill@eafit.edu.co; catrujilla@eafit.edu.co

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Mostrando 1 - 7 de 7

Digital opties tool for multi-purpose experimental applications
(2010-01-01) Sierra-Sosa, D.-E.; Angel-Toro, L.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
This work presents the results concerning the application of a Discrete Fresnel Transform algorithm (DFT), which was upgraded for modeling and experimenting with scalar diffraction fields, whose characteristics are analyzed. The MATLAB® software environment was used to implement this algorithm, which allows the user to set the initial conditions, corresponding to the optical information at the input plane, by using a graphic friendly user interface (GUI). Then, by using the DFT algorithm, light propagation from the input to the output plane is achieved. The outputs of the algorithm are the maps corresponding to the 2-D distributions amplitude and phase-modulo 2p, or equivalently, the corresponding real and imaginary parts of the complex analytical field. Also, to assist the analysis, line profiles for these maps are provided. Results allow the user synthesizing Fresnel diffraction in presence of multiple components, like lenses, prisms, diffractive gratings, and holographic elements. Indeed, by implementing a series of successive steps, applications like image forming and spatial filtering can be demonstrated. The basis of the algorithm's architecture and some typical results, which closely resemble those from the experiments, are presented.
An integrated system for virtual scene rendering, stereo reconstruction and accuracy estimation
(2006-01-01) Marichal-Hernández, J.G.; Pérez Nava, F.; Rosa, F.; Restrepo, R.; Rodríguez-Ramos, J.M.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
This article depicts an integrated system capable of generating virtual stereo scenes, reconstructing a three-dimensional map of distances, and calculating the accuracy of the results obtained. This tool is particularly useful for verifying the validity of distance reconstruction techniques, and is robust enough to use in a wide variety of scenarios since it avoids the need for an image-capture system in laboratory simulations. The importance of the distance reconstruction problem lies in the range of its applications: industrial inspection and quality control, surveillance and security, autonomous vehicles, robotic systems, medical image analysis, image databases, virtual reality, telepresence, and telerobotics. The system is based on the VRML standard for three-dimensional geometric scene representation, on OpenGL for rendering virtual scenes, and on the TRW algorithm for the problem of three-dimensional reconstruction. © 2006 IEEE.
Shack-Hartmann centroid detection using the spiral phase transform
(OSA - The Optical Society of America, 2012-01-01) Vargas, J.; Restrepo, R.; Estrada, J.C.; Sorzano, C.O.S.; Du, Y.-Z.; Carazo, J.M.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
We present a Shack-Hartmann (SH) centroid detection algorithm capable to measure in presence of strong noise, background illumination and spot modulating signals, which are typical limiting factors of traditional centroid detection algorithms. The proposed method is based on performing a normalization of the SH pattern using the spiral phase transform method and Fourier filtering. The spot centroids are then obtained using global thresholding and weighted average methods. We have tested the algorithm with simulations and experimental data obtaining satisfactory results. A complete MATLAB package that can reproduce all the results can be downloaded from [http://goo.gl/o2JhD]. © 2012 Optical Society of America.
Shack-Hartmann spot dislocation map determination using an optical flow method
(OPTICAL SOC AMER, 2014-01-27) Vargas, J.; Restrepo, R.; Belenguer, T.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
We present a robust, dense, and accurate Shack-Hartmann spot dislocation map determination method based on a regularized optical flow algorithm that does not require obtaining the spot centroids. The method is capable to measure in presence of strong noise, background illumination and spot modulating signals, which are typical limiting factors of traditional centroid detection algorithms. Moreover, the proposed approach is able to face cases where some of the reference beam spots have not a corresponding one in the distorted Hartmann diagram, and it can expand the dynamic range of the Shack-Hartmann sensor unwrapping the obtained dense dislocation maps. We have tested the algorithm with both simulations and experimental data obtaining satisfactory results. A complete MATLAB package that can reproduce all the results can be downloaded from [http://goo.gl/XbZVOr]. © 2014 Optical Society of America.
Soap film analysis by speckle interferometer
(SPIE-INT SOC OPTICAL ENGINEERING, 2003-01-01) Tebaldi, M.; Ángel, L.; Trivi, M.; Bolognini, N.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
In this paper a soap film is characterized by using a speckle interferometer. The arrangement consists of a double-exposure specklegram obtained through a double-aperture system, by introducing a wedge in front of one aperture in one exposure. It is assumed that a uniform displacement of the diffuser is produced between exposures. The average intensity distribution and the changes experimented by the interferometric fringe visibility in the Fourier plane due to the introduction of a soap film in each exposure are analyzed.
Speckle interferometric technique to assess soap films
(ELSEVIER SCIENCE BV, 2004-01-02) Tebaldi, M; Angel, L; Bolognini, N; Trivi, M; Universidad EAFIT. Departamento de Ciencias Básicas; 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.
Vortex-enhanced coherent-illumination phase diversity for phase retrieval in coherent imaging systems
(OSA - The Optical Society, 2016-04-15) Echeverri-Chacón, S.; Restrepo, R.; Cuartas-Vélez, C.; Uribe-Patarroyo, N.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
We propose a phase-retrieval method based on the numerical optimization of a new objective function using coherent phase-diversity images as inputs for the characterization of aberrations in coherent imaging systems. By employing a spatial light modulator to generate multiple-order spiral phase masks as diversities, we obtain an increase in the accuracy of the retrieved phase compared with similar state-of-the-art phase-retrieval techniques that use the same number of input images. We present simulations that show a consistent advantage of our technique, and experimental validation where our implementation is used to characterize a highly aberrated 4F optical system. (C) 2016 Optical Society of America

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Examinando Optica Aplicada por Materia "Algorithms"

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