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https://hdl.handle.net/10784/1123

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Analysis of a developed analog trilateration system of impulsive sounds
(SPIE-INT SOC OPTICAL ENGINEERING, 2014-01-01) López R., J.M.; Marulanda B., J.I.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
A characterization study is made from a trilateration system for impulsive sounds, in which theoretical analysis and experimental results are presented. This system uses an analog trilateration method, avoiding to implement high frequency ADC conversion elements. It also presents the optimization of the chosen array of microphones, thus allowing for a better trilateration algorithm behavior. © 2014 SPIE.
Analysis of chemical processes for the synthesis of magnetite for biomedical applications
(IOP PUBLISHING LTD, 2011-01-01) Baena, J.; Marulanda, J.I.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
This article demonstrates the evaluation of wet chemical routes to produce magnetic nanoparticles of iron oxide and surface chemistry characterization by infrared spectroscopy (IR). Its potential use in biomedicine as contrast agents or to deliver drugs in localized medical treatments, which reduce the toxicity associated with cytotoxic drugs, is also evaluated.
Analysis of optomechanicalMethod for materials selection in optical design
(OSA - The Optical Society, 2016-01-01) Cano-Barrera, C.; Restrepo, R.; Zuluaga-Ramírez, P.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
We present a technique to determine the wavefront error and polarization changes introduced by a loaded optical material based on its optical, thermal and mechanical properties through an integrated optomechanical simulation process. © OSA 2016.
Analysis of vibrations in a plate using interferometric methods
(SPIE-INT SOC OPTICAL ENGINEERING, 2004-01-01) Rueda, E.; Angel, L.; Velasquez, D.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
In this work some frequencies and modes of vibration of a thin plate were determined using interferometric methods like: real-time holographic interferometry, time-average holographic interferometry, digital speckle pattern interferometry DSPI. And the results obtained are compared with those obtained with the program of finite elements COSMOS.
Analysis of vibrations in a plate using interferometric methods
(SPIE, 2004-10-21) Ángel-Toro, Luciano; Prieto, Daniel Velasquez; Rueda Muñóz, Edgar Alberto; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
In this work some frequencies and modes of vibration of a thin plate were determined using interferometric methods like: real-time holographic interferometry, time-average holographic interferometry, digital speckle pattern interferometry DSPI. And the results obtained are compared with those obtained with the program of finite elements COSMOS.
Applications of spatial light modulators in speckle interferometry
(SPIE-INT SOC OPTICAL ENGINEERING, 2012-01-01) Bodendorfer, T.; Restrepo, R.; Belenguer, T.; Koch, A.W.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
High resolution spatial light modulators (SLM) have been used in many different ways during the last years. Regarding speckle interferometry, different applications can be realized by integrating SLMs in interferometric setup. In this work the influence of a liquid crystal based phase-only SLM on the measurement quality concerning deformation and shape measurement using two wavelengths is discussed. © 2012 Copyright SPIE.
A computational method to acquired hogel images used in full parallax holographic stereograms
(OSA - The Optical Society, 2016-01-01) Sánchez, A.M.; Velásquez, D.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
Holographic stereogram displays require 2D image sequences with a distribution of multiple perspectives of the object. This paper propose a computational method to generate the required images to record full parallax holographic stereograms. © OSA 2016.
Computer graphic method for direct correspondence image acquisition used in full parallax holographic stereograms
(SPIE-INT SOC OPTICAL ENGINEERING, 2016-01-01) Madrid Sanchez, Alejandro; Velasquez Prieto, Daniel; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
The holoprinter technology based on holographic stereograms has generated a fast development in holographic display applications by the holographic recording of a 2D image sequence with information of a 3D scene, which could be real or computer generated. The images used in holographic stereograms initially start from the acquisition of the different image perspectives of the 3D scene by the re-centering camera configuration and then, this images must be rearranged before the optical recording. This paper proposes a method to acquire the required images or hogel images in one step without using rearrange algorithms, the method uses a virtual camera that moves along a virtual rail by conventional computer graphics software. The proposed method reduced the time required to obtain the hogel images and enhance the quality of the 3D holographic images; it also can be applied in different computer graphics software. To validate the method, a full parallax holographic stereogram was made for a computer generated object.
Consumed fatigue life assessment of composite material structures by optical surface roughness inspection
(Trans Tech Publications Ltd., 2013-01-01) Zuluaga, P.; Frövel, M.; Restrepo, R.; Trallero, R.; Atienza, R.; Pintado, J.M.; Belenguer, T.; Salazar, F.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
A strong knowledge of the fatigue state of highly advanced carbon fiber reinforced polymer composite (CFRP) structures is essential to predict the residual life and optimize intervals of structural inspection, repairs, and/or replacements. Current techniques are based mostly on measurement of structural loads throughout the service life by electric strain gauge sensors. These sensors are affected by extreme environmental conditions and by fatigue loads in such a way that the sensors and their systems require exhaustive maintenance throughout system life. This work is focused on providing a new technique to evaluate the fatigue state of CFRP structures by means of evaluating the surface roughness variation due to fatigue damage. The surface roughness is a property that can be measured in the field by optical techniques such as speckle and could be a useful tool for structural health monitoring. The relation between surface roughness and fatigue life has been assessed on CFRP test specimens. A tensile fatigue load with an R=0.1 (T-T) and a maximum load of 60% of the material ultimate strength has been applied. The surface roughness of the specimens has been determined from the surface topography measured by a high precision confocal microscope. Results show that the surface roughness of the specimens increases with the accumulation of fatigue cycles in such a way that the roughness could be taken into account as a fatigue damage metrics for CFRP. © (2013) Trans Tech Publications.
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.
DC term filtering techniques in digital holography
(SPIE, 2004-10-21) Velásquez-Prieto, Daniel; García Sucerquia, Jorge Iván; Herrera Ramírez, Jorge Alexis; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
In numerical hologram reconstruction like in optical holography, there exist different diffraction orders, which many times produce difficulties for the image visualizations. In numerical reconstruction, the filtering of the DC term, or zero order diffraction, provides an improved utilization of the dynamic range of the visualization systems, which is needed for the right displaying purposes of reconstructed images. In the case of the in-line set-ups, the zero diffraction order has even more devastating effects because it does not allow reconstructing the images itself as in Gabor's holograms, so it is necessary to attempt a filtering of this DC term. In this work is shown a qualitative assessment of different techniques of DC term filtering applied to numerical reconstruction of Fresnel's holograms recorded by means of off-line set-ups.
DC term filtering techniques in digital holography
(SPIE-INT SOC OPTICAL ENGINEERING, 2004-01-01) Garcia-Sucerquia, J.; Ramirez, J.A.H.; Prieto, D.V.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
In numerical hologram reconstruction like in optical holography, there exist different diffraction orders, which many times produce difficulties for the image visualizations. In numerical reconstruction, the filtering of the DC term, or zero order diffraction, provides an improved utilization of the dynamic range of the visualization systems, which is needed for the right displaying purposes of reconstructed images. In the case of the in-line set-ups, the zero diffraction order has even more devastating effects because it does not allow reconstructing the images itself as in Gabor's holograms, so it is necessary to attempt a filtering of this DC term. In this work is shown a qualitative assessment of different techniques of DC term filtering applied to numerical reconstruction of Fresnel's holograms recorded by means of off-line set-ups.
Design of a control system for interferometric fringe stabilization system with remote access
(SPIE-INT SOC OPTICAL ENGINEERING, 2013-01-01) Espitia-Gomez, Javier; Angel-Toro, Luciano; Velasquez, 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 SPIE.
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.
Design of a linear in wavenumber spectrometer
(OSA - The Optical Society, 2018-01-01) Ruiz-Lopera S.; Restrepo R.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
We describe the optical design of a linear in wavenumber spectrometer that combines a grating and a prism. OpticStudio software was used to validate the performance of the design. High lineartiy in k-space was achived. © 2018 The Author (s)
Design, development, and implementation of a low-cost full-parallax holoprinter
(SPIE-INT SOC OPTICAL ENGINEERING, 2018-02-19) Madrid S, A.; D. Velásquez; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
Synthetic holograms have achieved a great impact in a variety of fields like architecture, advertising, army and art, and have proven their importance in advancing the holographic displays as visual communication media. Printing synthetic holograms needs the development of a holographic printer that from a set of 2D images allows to create 3D holographic images of real objects and computer generated objects. With the purpose of developing a holoprinter, we have implemented three related components: i) design and implementation of an optical system for direct writing of hogels, ii) a computational implementation to generate parallax 2D images and finally, iii) the implementation of an opto-mechanical and control system for automatic recording of the synthetic holograms. The three components have been developed under the restricted conditions of our holographic laboratory. In this way, a direct write optical setup was implemented using He-Ne laser, and an optical system for hogel writing with a field of view (FOV) of 60° was designed by using commercial lenses. To generate 2D parallax images, an application was created in the free computer graphics software Blender, applying different camera configurations. And a LabView application was made to automatically control obturation and displacement of the holographic plate. The system developed can record computer generated objects and real objects. Real objects are digitized by using a conventional photographic camera. Reflection full parallax holographic stereograms were recorded on PFG-01 plates and their holographic reconstructions are presented and discussed. Copyright © 2018 SPIE. Downloading of the abstract is permitted for personal use only.
Detection of saharan mineral dust aerosol transport over brazilian northeast through a depolarization lidar
(EDP Sciences, 2018-01-01) Guedes A.G.; Landulfo E.; Montilla-Rosero E.; Lopes F.J.S.; Hoelzemann J.J.; Fernandez J.H.; Silva M.P.A.; Santos R.S.S.; Guerrero-Rascado J.L.; Alados-Arboledas L.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
In this study we present results of linear volume depolarization ratio profiles obtained by a depolarization lidar in operation in Natal, Brazil. The DUSTER system has 4 channels, namely: 1064, 532 s/p and 355 nm. This system is calibrated with a half-wave plate using the 90° methodology. The data obtained from this system is correlated with AERONET sunphotometer data, and, when available, CALIPSO satellite data. In addition a trajectory model (HYSPLIT) is used to calculate backward trajectories to assess the origin of the dust polluted air parcels. The objective is to create a transport database of Saharan dust. © The Authors, published by EDP Sciences, 2018.
Digital Optics Tool for Multi-Purpose Experimental Applications
(INT INST INFORMATICS & SYSTEMICS, 2010-07-02) Sierra-Sosa, D.; Angel 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 (R) 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 2 pi, 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.
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.
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.

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