Person:
Vargas Balbuena, Javier

First Name

Javier

Last Name

Vargas Balbuena

URI

https://hdl.handle.net/20.500.14352/75168

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Óptica

Area

Optica

Identifiers

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Now showing 1 - 10 of 33

Two-step interferometry by a regularized optical flow algorithm
(Optics Letters, 2011) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Sánchez Sorzano, Carlos Óscar; Estrada, Julio César; Carazo García, José María
A two-step phase-shifting method, that can demodulate open-and closed-fringed patterns without local sign ambiguity is presented. The proposed method only requires a constant phase-shift between the two interferograms. This phase-shift does not need to be known and can take any value inside the range (0, 2 π), excluding the singular case where it corresponds to π. The proposed method is based on determining first the fringe direction map by a regularized optical flow algorithm. After that, we apply the spiral phase transform (SPT) to one of the fringe patterns and we determine its quadrature signal using the previously determined direction. The proposed technique has been applied to simulated and experimental interferograms obtaining satisfactory results. A complete MATLAB software package is provided in [http://goo.gl/Snnz7].
Direct demodulation of closed-fringe interferograms based on active contours
(Optics Letters, 2010) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Belenguer Dávila, Tomás
We demonstrate a method to directly demodulate closed-fringe interferograms using a kind of active contour called a snake. This method can be used to demodulate a single closed-fringe interferogram when its background illumination and/or contrast terms have a spatial frequency similar to the spatial frequency of the equivalent normalized interferogram. Among other cases, this problematic usually appears in interferometry when spurious reflection appears in the interferogram. In these situations, typical Fourier-based methods are of no help. We show a set of simulations and experimental results that prove the effectiveness of the proposed method.
High dynamic range imaging method for interferometry
(Optics Communications, 2011) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Restrepo, R.; Belenguer Dávila, Tomás
We demonstrate a method to easily and quickly extend the dynamic range imaging capabilities of the camera in a typical interferometric approach. The camera dynamic range is usually low and limited to 256 gray levels. Also, it is well known that one may have over or under-exposed regions in the interferogram (due to non-uniform illumination) which makes these image regions not reliable. In our proposed method it is not necessary to obtain or use the non-linear camera response curve in order to extend the camera dynamic range. We obtain a sequence of differently exposed interferograms, typically five or six; after that, we compute the corresponding normalized fringe patterns and modulation maps using a typical normalization method. These normalized patterns are combined through a temporal weighted average using as weights the corresponding modulation maps. We show a set of experimental results that prove the effectiveness of the proposed method.
Non-uniformly polarized beams across their transverse profiles: an introductory study for undergraduate optics courses
(European Journal of Physics, 2004) Piquero Sanz, Gemma María; Vargas Balbuena, Javier
We provide a simple theoretical study of beams non-uniformly polarized across their transverse sections which can be introduced in undergraduate optics courses. In order to generate such beams we propose to use a slightly convergent (or divergent) linearly and uniformly polarized beam impinging on an anisotropic uniaxial material with the beam propagation direction along the optic axis. Analytical expressions for the Jones vector, Stokes parameters, ellipticity and azimuth at each point of the transverse section, perpendicular to the propagation direction, are obtained at the output of this system. By means of these parameters a detailed description of the state of polarization across the transverse profile is given.
Incremental PCA algorithm for fringe pattern demodulation
(Optics express, 2022) Gómez Pedrero, José Antonio; Estrada, Julio César; Alonso Fernández, José; Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier
This work proposes a new algorithm for demodulating fringe patterns using principal component analysis (PCA). The algorithm is based on the incremental implantation of the singular value decomposition (SVD) technique for computing the principal values associated with a set of fringe patterns. Instead of processing an entire set of interferograms, the proposed algorithm proceeds in an incremental way, processing sequentially one (as minimum) interferogram at a given time. The advantages of this procedure are twofold. Firstly, it is not necessary to store the whole set of images in memory, and, secondly, by computing a phase quality parameter, it is possible to determine the minimum number of images necessary to accurately demodulate a given set of interferograms. The proposed algorithm has been tested for synthetic and experimental in ter ferograms showing a good performance. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
Windowed phase unwrapping using a first-order dynamic system following iso-phase contours
(Applied Optics, 2012) Quiroga Mellado, Juan Antonio; Estrada, Julio C.; Vargas Balbuena, Javier; Flores Moreno, Mauricio J.
In this work, we show a windowed phase-unwrapping technique that uses a first-order dynamic system and scans the phase following its iso-phase contours. In previous works, we have shown that low-pass first-order dynamic systems are very robust and useful in phase-unwrapping problems. However, it is well known that all phase-unwrapping methods have a minimum signal-to-noise ratio that they tolerate. This paper shows that scanning the phase within local windows and using a path following strategy, the first-order unwrapping method increases its tolerance to noise. In this way, using the improved approach, we can unwrap phase maps where the basic dynamic phase-unwrapping system fails. Tests and results are given, as well as the source code in order to show the performance of the proposed method.
Local fringe density determination by adaptive filtering
(Optics Letters, 2011) Vargas Balbuena, Javier; Quiroga Mellado, Juan Antonio; Belenguer Dávila, Tomás
We demonstrate a method to easily and quickly determine the local fringe density map of a fringe pattern. The method is based on an isotropic adaptive bandpass filter that is tuned at different frequencies. The modulation map after applying a specific bandpass frequencies filter presents a maximum response in the regions where the bandpass filter and fringe frequencies coincide. We show a set of simulations and experimental results that prove the effectiveness of the proposed method.
Advances in Xmipp for cryo-electron microscopy: from Xmipp to Scipion
(Molecules, 2021) Strelak, David; Jiménez Moreno, Amaya; Vilas, José Luis; Ramírez Aportela, Erney; Sánchez García, Rubén; Maluenda, David; Vargas Balbuena, Javier; Herreros, David; Fernández Giménez, Estrella; Isidro Gómez, Federico P. de; Horacek, Jan; Myska, David; Horacek, Martin; Conesa, Pablo; Fonseca-Reyna, Yunior C.; Jiménez, Jorge; Martínez, Marta; Harastani, Mohamad; Jonic, Slavica; Filipovic, Jiri; Marabini, Roberto; Carazo, José María; Sorzano, Carlos O. S
Xmipp is an open-source software package consisting of multiple programs for processing data originating from electron microscopy and electron tomography, designed and managed by the Biocomputing Unit of the Spanish National Center for Biotechnology, although with contributions from many other developers over the world. During its 25 years of existence, Xmipp underwent multiple changes and updates. While there were many publications related to new programs and functionality added to Xmipp, there is no single publication on the Xmipp as a package since 2013. In this article, we give an overview of the changes and new work since 2013, describe technologies and techniques used during the development, and take a peek at the future of the package.
Nuevos métodos de medida 3D mediante triangulación activa
(2010) Vargas Balbuena, Javier; Quiroga Mellado, Juan Antonio
Los métodos ópticos basados en triangulación activa han experimentado un gran avance en la pasada década y están comenzando a sustituir a los sensores tridimensionales basados en contacto en las diversas aplicaciones industriales de estos dispositivos. Estos métodos ópticos tienen propiedades que los hacen muy interesantes, como su gran velocidad, su capacidad de medida sin contacto y a campo completo y su bajo coste. No obstante, estos métodos presentan limitaciones prácticas cuando se está interesado en medir objetos extensos con gran precisión. En primer lugar los métodos de calibración para estos sistemas con los que se obtiene los resultados más precisos son muy difíciles de utilizar cuando se está interesado en calibrar un volumen de gran tamaño. Por otra parte, los sistemas de medida 3D basados en triangulación activa están caracterizados por tener una relación fija entre el área escaneada y la resolución en profundidad obtenida. Si se desea inspeccionar un área extensa se debe esperar obtener una resolución en profundidad pobre. Para obtener una medida 3D de un área extensa con alta resolución en profundidad es necesario realizar una medida en multiresolución. Finalmente, los métodos de triangulación activa estándares no son aplicables en el caso de que se desee inspeccionar una superficie no-cooperativa con una gran resolución espacial. Las superficies no-cooperativas se caracterizan por presentar una gran variación espacial de la reflectividad, de forma que existen regiones muy brillantes y muy oscuras. En la presenta memoria de tesis se presentan nuevos métodos de medida 3D mediante triangulación activa para resolver los problemas anteriormente mencionados. Por una parte, se introduce un nuevo método de calibración mixto para un sistema de triangulación activa que permite calibrar con gran precisión volúmenes de gran tamaño. Adicionalmente, se presentan dos nuevos métodos para la medida en multiresolución, uno local y otro global y finalmente se presenta un método para la medida 3D de superficies no-cooperativas.
Fringe pattern denoising by image dimensionality reduction
(Optics and Lassers in Engineering, 2013) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Estrada, Julio César; Carazo García, José María; Sánchez Sorzano, Carlos Óscar
Noise is a key problem in fringe pattern processing, especially in single frame demodulation of interferograms. In this work, we propose to filter the pattern noise using a straightforward, fast and easy to implement denoising method, which is based on a dimensionality reduction approach, in the sense of image rank reduction. The proposed technique has been applied to simulated and experimental ESPI interferograms obtaining satisfactory results.