Person:
Quiroga Mellado, Juan Antonio

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First Name
Juan Antonio
Last Name
Quiroga Mellado
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Óptica
Area
Optica
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UCM identifierORCIDScopus Author IDDialnet IDGoogle Scholar ID

Search Results

Now showing 1 - 10 of 23
  • Publication
    Wavefront measurement by solving the irradiance transport equation for multifocal systems
    (Spie-Soc Photo-Optical Instrumentation Engineers, 2001-12) Quiroga Mellado, Juan Antonio; Gómez Pedrero, José Antonio; Martínez Antón, Juan Carlos
    A method for sensing wavefronts is presented. The method is based on the resolution of the irradiance transport equation, which relates the irradiance distribution and the shape of the wavefront of a light beam propagating along a given direction. The method presents no restrictions in the locations of the measurement planes and incorporates an improved procedure to geometrically correct the acquired images to take into account the effect of ray deflection in the propagation of the irradiance distributions. With the proposed technique, we measure the wavefront at the exit pupil of a progressive addition lens and find good agreement with an alternative deflectometric method.
  • Publication
    Robust isoclinic calculation for automatic analysis of photoelastic fringe patterns
    (SPIE--The International Society for Optical Engineering, 2008) Quiroga Mellado, Juan Antonio; Pascual Ramírez, Sergio; Villa Hernández, José de Jesús
    There are two main steps in the analysis of photoelastic fringe patterns: the isoclinics and isochromatics computation. For the isochromatic computation there exist several possibilities but one of the best, from the point of view of reliability and automatization, is the phase shift technique. However all phase shift isochromatic algorithms need a good estimation of the isoclinic direction angle that is a challenging task in presence of low birrefringence, isotropic points and monochromatic illumination. In this work we discuss the application of a novel isoclinic direction calculation method based in a phase shifting technique and a fast direction estimation regularized filter. Experimental results show that the proposed method together with a standard phase shifting isochromatic estimation is a good option for the automatic analysis of photoelastic fringe patterns under different illumination conditions, load levels and sample complexity, making possible further processing steps as full-field stress separation.
  • Publication
    Recent advances in automatic demodulation of single fringe patterns
    (Springer Verlag Berlin, 2006) Quiroga Mellado, Juan Antonio; Crespo Vázquez, Daniel; Gómez Pedrero, José Antonio; Martínez Antón, Juan Carlos
  • Publication
    Temporal phase evaluation by Fourier analysis of fringe patterns with spatial carrier
    (Taylor and Francis Ltd., 2001-11-20) Quiroga Mellado, Juan Antonio; Gómez Pedrero, José Antonio
    A new method is presented for the temporal evaluation of fringe patterns with spatial carrier. The proposed technique involves recording the irradiance fluctuations obtained when a linear variation of the set-up sensitivity is introduced. In this condition, the use of a spatial carrier introduces a linear temporal carrier frequency. In this way, Fourier analysis can be performed to obtain the phase and, finally, the quantity to be measured. The optimum conditions for the sensitivity variation have been studied in order to minimize the errors associated with the Fourier analysis. The technique has been applied to measure the distribution of ray deflections on the surface of two ophthalmic lenses using a deflectometric set-up.
  • Publication
    A isotropic n-dimensional quadrature transform and its applications in fringe pattern processing
    (SPIE--The International Society for Optical Engineering, 2003) Quiroga Mellado, Juan Antonio; Servín Guirado, Manuel; Marroquín Zaleta, José Luis; Gómez Pedrero, José Antonio
    In fringe pattern processing, quadrature operators are useful to obtain the corresponding modulating phase. In the case that a carrier exists (spatial or temporal), there are good methods for phase demodulation as Fourier analysis and asynchronous methods, for example. However, if there is no carrier or is to low, robust demodulation from a single image is a difficult task. In this work we present some recent advances in the processing of single fringe patterns with closed fringes based in a isotropic n-dimensional quadrature transform. In particular we address several problems related with the application of this quadrature operator. One of these problems is the Fringe direction, its role in the demodulation process is discussed and a practical method for its computation is presented. Fringe pattern normalization is also an important subject in the demodulation process from a singe image, taking this into account we present a technique for isotropic fringe pattern normalization based in the n-dimensional quadrature transform. All these techniques together configure a robust method for automatic demodulation of single fringe patterns. The performance and limitations of the method are discussed and illustrated by experimental results.
  • Publication
    Structured light-based NDT techniques of interest in the aerospace industry
    (The British Institute of Non-Destructive Testing, 2003-04) Quiroga Mellado, Juan Antonio; Martínez Antón, Juan Carlos; Gómez Pedrero, José Antonio
    Structured light techniques (Moiré, projected fringes and other pattern projection techniques) have been used for many years in the aerospace and other industries for external defect location and characterization, 3D shape, deformation measurements and the like. The application of digital image processing methods to the images generated by these techniques has made possible the realization of fast and automatic systems for quantitative NDT measurements. This work is divided in two parts. First, the principal approaches to structured light-based NDT are reviewed, presenting the basis, performance characteristics as well as their expected ranges and resolutions. The second part concentrates on the digital image processing techniques of interest in the field of structured light-based NDT. As the images produced by these techniques are often in the form of phase-modulated fringe patterns, the branch of image processing that deal with this kind of images is denominated fringe pattern processing. Among the many existing fringe pattern processing techniques, the paper will concentrate on the phase-shifting methods (spatial and temporal) and the regularization and natural demodulation methods. It will be shown how when acquisition time is not critical, and several phase-shifted images can be acquired, phase-shifting techniques are well-suited for phase demodulation. Related with these techniques is the so-called phase unwrapping problem that will be discussed. Finally, fringe pattern processing techniques are discussed which can be applied in cases when acquisition time or the optical set-up only allows the use of one fringe pattern. In this case the problem of demodulating the phase is ill-posed from a mathematical point of view and special techniques as regularization and the so-called natural demodulation are needed.
  • Publication
    Automatic demodulation of single-image fringe patterns with application in the evaluation of external defects in aeronautical surfaces by shadow-moire
    (VDI-VDE - Verlag GMBH, 2004) Quiroga Mellado, Juan Antonio; Crespo Vázquez, Daniel; Fournier, N.; Martínez Antón, Juan Carlos
    Automatic demodulation of single-image fringe patterns is of great importance in research areas were it is difficult to apply standard phase evaluation techniques such as phase sampling or Fourier transform methods. In this work we will present recent advances in the automatic demodulation of single-image fringe patterns. In particular we have used two methods for the demodulation process: the regularized phase tracker (RPT) and the isotropic quadrature transform (IQT). For a reliable and automatic demodulation of real fringe patterns by means of the RPT and the IQT techniques we have developed strategies for fringe pattern normalization, modulo 2π fringe orientation computation and adaptive processing, which all together configure a reliable and fast demodulation scheme. We have applied these techniques in the evaluation of external defects in aeronautical surfaces by the shadow moire technique and for this purpose a software package has been developed that works together with an in-line inspection system for indentation assessment designed by the company NDT-Expert. Experimental results of the system will be shown and performance will be discussed.
  • Publication
    Adaptive spatiotemporal structured light method for fast three-dimensional measurement
    (Spie-Soc Photo-Optical Instrumentation Engineers, 2006-10) Quiroga Mellado, Juan Antonio; Crespo Vázquez, Daniel; Vargas Balbuena, Javier; Gómez Pedrero, José Antonio
    We present a high-speed 3-D spatiotemporal shape measurement technique by means of structured light. Current methods use a constant number of images that do not take into account the available temporal continuity of the measured object. That is, they focus on acquiring and processing as quickly as possible a fixed number of images to solve for the correspondence problem and later obtain the 3-D shape by triangulation. The number of images used imposes the use of some spatial support. The major contribution of our research is a new spatiotemporal scheme that, depending on the object's movement, adaptively uses the maximum number of projected images consistent with the local temporal continuity, therefore solving the correspondence problem with the minimum possible spatial support for each position. This is achieved by the use of a hybrid color pattern composed of an analog sinusoidal periodic code in the red channel and a digital binary spatial code in the blue channel that is cyclically displaced. No subpixel calculation is used and it is possible to implement error correction strategies that make the method fast and reliable, enabling dynamic online 3-D measurement of objects in movement.
  • Publication
    XtremeFringe: state-of-the-art software for automatic processing of fringe patterns
    (SPIE--The International Society for Optical Engineering, 2007) Quiroga Mellado, Juan Antonio; Crespo Vázquez, Daniel; Gómez Pedrero, José Antonio
    XtremeFringe is a new library for fringe pattern processing which incorporates modem methods for automatic analysis including fringe pattern demodulation, fringe pattern filtering and phase unwrapping methods. XtremeFringe (R) is written in C# and is usable as an assembly from any NET language (C#, C++, .NET, J#) and additionally as a Matlab toolbox, which ensures an easy adaptation in custom applications, providing the user with a versatile and powerful tool for fringe pattern analysis in a flexible way. The functions of XtremeFringe are suitable to be employed in metrological applications such interferometry, photoelasticity, Moire techniques, holography, etc. supplying the user with up-to-date fringe analysis tools. In this work, we demonstrate the capabilities of the XtremeFringe library, processing different examples showing the ability of the library to analyze complex fringe patterns in a fast, reliable and automatic way.
  • Publication
    Real discontinuity preservation algorithm for ESPI fracture measuring
    (SPIE--The International Society for Optical Engineering, 2002) Quiroga Mellado, Juan Antonio; Rodríguez Vera, Ramón; Rayas Álvarez, Juan Antonio; Marroquín Zaleta, José Luis; Rivera, Mariano
    A well-founded and computationally fast method is presented for filtering and interpolating noisy and discontinuous wrapped phase fields that preserves both the 2π discontinuities that come from the wrapping effect and the true discontinuities that may be present. It also permits the incorporation of an associated quality map, if it is available, in a natural way. Examples of its application to the computation recovery of discontinuous phase fields from speckle interferometry fracture measuring are presented.