Person:
Quiroga Mellado, Juan Antonio

First Name

Juan Antonio

Last Name

Quiroga Mellado

URI

https://hdl.handle.net/20.500.14352/75019

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Óptica

Area

Optica

Identifiers

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Search Results

Now showing 1 - 10 of 22

Multiresolution approach based on projection matrices
(Applied Optics, 2009) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier
Active triangulation measurement systems with a rigid geometric configuration are inappropriate tor scanning large objects with low measuring tolerances. The reason is that the ratio between the depth recovery error and the lateral extension is a constant that depends on the geometric setup. As a consequence, measuring large areas with low depth recovery error requires the use of multiresolution techniques. We propose a multiresolution technique based on a camera-projector system previously calibrated. The method consists of changing the camera or projector's parameters in order to increase the system depth sensitivity A subpixel retroprojection error in the self-calibration process and a decrease of approximately one order of magnitude in the depth recovery error can be achieved using the proposed method.
Deflectometric method for the measurement of user power for ophthalmic lenses
(Applied Optics, 2010) Quiroga Mellado, Juan Antonio; Gómez Pedrero, José Antonio; Alonso Fernández, José; Vargas Balbuena, Javier
This paper presents a deflectometric technique to measure the power of an ophthalmic lens as perceived by the user. It is based on a calibrated camera acting as a pinhole in order to measure ray deflection along the same path as the visual axis when the lens is held in front of the eye. We have analyzed numerically the accuracy of our technique, and it has been compared experimentally with a commercial "lens mapper" and with the real user power calculated from the measured topography of the lens surfaces to state the reliability and accuracy of the presented technique.
Project number: 54
Desarrollo de material docente audiovisual online de apoyo para la asignatura: dispositivos de instrumentación óptica
(2023) Vargas Balbuena, Javier; Diez Garrote, Francisco; Quiroga Mellado, Juan Antonio; Canabal Boutureira, Héctor Alfonso; Boiso Calero, Antonio
En este proyecto de innovación docente se han desarrollado una serie de videos cortos para fijar visualmente conceptos clave sobre instrumentación óptica. Estos videos están enfocados en la mejora de la compresión y análisis de los estudiantes de la asignatura Dispositivos de Instrumentación Óptica de cuarto curso del Grado en Físicas. Es decir, nuestro objetivo es proporcionar a los estudiantes con experiencias virtuales de laboratorio que les permitan entender de forma sencilla y rápida conceptos esenciales de la asignatura. También estos videos serán utilizados en el aula por los profesores como material docente de apoyo.
Optical inspection of liquid crystal variable retarder inhomogeneities
(Applied Optics, 2010) Quiroga Mellado, Juan Antonio; Uribe Patarroyo, Néstor R.; Vargas Balbuena, Javier; Álvarez Herrero, Alberto; Belenguer Dávila, Tomás
Liquid crystal variable retarders (LCVRs) are starting to be widely used in optical systems because of their capacity to provide a controlled variable optical retardance between two orthogonal components of incident polarized light or to introduce a known phase shifting (PS) between coherent waves, both by means of an applied voltage. Typically, the retardance or PS introduced by an LCVR is not homogeneous across the aperture. On the one hand, the LCVR glass substrates present a global bend that causes an overall variation of the retardance or PS. On the other hand, in the manufacturing process of an LCVR, there sometimes appears a set of micro-air bubbles that causes local retardance or PS inhomogeneities. In this work, we present an interferometric technique based on a Mach-Zehnder interferometer that is insensitive to vibrations and capable of inspecting and characterizing the LCVR's retardance or PS inhomogeneities. The feasibility of the proposed method is demonstrated in the experimental results, where the LCVR retardance is measured with an error of about 0:2 rad. The thickness of possible micro-air bubbles is obtained with a resolution of about 50 nm.
Analysis of the principal component algorithm in phase-shifting interferometry
(Optics Letters, 2011) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Belenguer Dávila, Tomás
We recently presented a new asynchronous demodulation method for phase-sampling interferometry. The method is based in the principal component analysis (PCA) technique. In the former work, the PCA method was derived heuristically. In this work, we present an in-depth analysis of the PCA demodulation method.
Multiplicative phase-shifting interferometry using optical flow
(Applied Optics, 2012) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Estrada, Julio C.; Sánchez Sorzano, Carlos Óscar; Servín Guirado, Manuel
Fringe patterns with a multiplicative phase shift among them appear in experimental techniques as photoelasticity and RGB shadow moiré, among others. These patterns cannot be processed using standard phase-shifting demodulation techniques. In this work, we propose to use a multiframe regularized optical flow algorithm to obtain the interesting modulating phase. The proposed technique has been applied to simulated and experimental interferograms obtaining satisfactory results.
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.
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].
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.