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 109

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.
Synchronous detection technique for temporal fringe pattern analysis
(Optics Communications, 2002) Quiroga Mellado, Juan Antonio; Villa, J.; Gómez Pedrero, José Antonio
An alternative method for temporal evaluation of fringe patterns is proposed. The method is based on the application of a synchronous detection system for processing the temporal irradiance fluctuations generated when the sensitivity of the optical set-up is changed. The technique requires an easy computing implementation and presents good noise rejection characteristics, In particular, the proposed method does not require to store the whole set of fringe images as it happens with Fourier techniques which allows for a faster data processing. Results of this method proved on synthetic fringe images as well as in real experiments are presented.
Histogram-based method for contrast measurement
(Applied Optics, 2000) Quiroga Mellado, Juan Antonio; Sánchez Brea, Luis Miguel; García Botella, Ángel; Bernabeu Martínez, Eusebio
A histogram-based technique for robust contrast measurement is proposed. The method is based on fitting the histogram of the measured image to the histogram of a model function, and it can be used for contrast determination in fringe patterns. Simulated and experimental results are presented.
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.
Fourier based design of asynchronous phase detection algorithms
(Optical Measurement Systems For Industrial Inspection V, Pts 1 And 2, 2007) Quiroga Mellado, Juan Antonio; Gómez Pedrero, José Antonio; Crespo Vázquez, Daniel
Phase detection is an important issue when dealing with optical metrology techniques for which the magnitude to be measured is encoded through the phase of a given fringe pattern. Asynchronous phase detection techniques are employed when the rate of phase change (frequency) it is not known. These techniques always present a variable frequency response, in other words, their ability to recover properly the phase depends strongly on the local frequency. In many experiments, it is possible to have a rough knowledge about the range of frequencies involved. Therefore, it constitutes a great advantage to have a procedure to design an asynchronous demodulation method which is suited to a particular frequency response for a given experiment. In this way, we get a better behaviour against noise which leads to more accurate and reliable phase extraction. In this work we present a technique to design asynchronous demodulation algorithms with a desired frequency response using a Fourier-based technique. The method allows the design of algorithms with a limited algebraic error in the recovered phase which have better properties than standard asynchronous phase detection techniques as it is shown in numeric and real experiments.
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.
Estimation of the orientation term of the general quadrature transform from a single n-dimensional fringe pattern
(Journal of The Optical Society Of America A-Optics Image Science and Vision, 2005) Quiroga Mellado, Juan Antonio; Servín Guirado, Manuel; Marroquín Zaleta, José Luis; Crespo Vázquez, Daniel
The spatial orientation of the fringe has been demonstrated to be a key point in the reliable phase demodulation from a single n-dimensional fringe pattern regardless of the frequency spectrum of the signal. The recently introduced general n-dimensional quadrature transform (GQT) makes explicit the importance of the fringe orientation in the demodulation process. The GQT is a quadrature operator that transforms cos φ into -sin φ-where φ is the modulating phase-and it is composed of two terms: an orientation factor directly related to the fringe's spatial orientation and an isotropic n-dimensional generalization of the one-dimensional Hilbert transform. We present a method for the determination of the orientation factor in a general n-dimensional case and its application to the demodulation of a single fringe pattern by the GQT. We have tested the algorithm with simulated as well as real photoelastic fringe patterns with good results.
Automatic processing in Moiré deflectometry by local fringe direction calculation
(Applied Optics, 1998) Canabal Boutureira, Héctor Alfonso; Quiroga Mellado, Juan Antonio; Bernabéu Martínez, Eusebio
An algorithm for accurately extracting the local fringe direction is presented. The algorithm estimates, in the neighborhood of n × n points, the direction of the gradient that points normal to the local fringe direction. The performance of four different derivative kernels is also compared. Since this method is sensitive to noise and variations in background and amplitude, a preprocessing step is used to limit these error sources. The method has been applied to the moiré deflectogram of a spherical and a progressive addition ophthalmic lens, resulting in a map of the refractive power of these lenses. The results are compared with the data obtained with a commercial focimeter. This technique is useful for analyzing the fringe patterns where the fringe direction is variable and must be obtained locally.