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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Search Results

Now showing 1 - 10 of 33
  • Publication
    Windowed phase unwrapping using a first-order dynamic system following iso-phase contours
    (The Optical Society Of America, 2012-11-12) 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.
  • Publication
    Anisotropic phase-map denoising using a regularized cost-function with complex-valued Markov-random-fields
    (Elsevier Sci. Ltd., 2010-06) Quiroga Mellado, Juan Antonio; Villa Hernández, José de Jesús; Rodríguez-Vera, Ramón; Rosa Vargas, José Ismael de la; González Ramírez, Efrén
    In our recently reported work [1] (Villa et al., 2009) we derived a regularized quadratic-cost function, which includes fringe orientation information, for denosing fringe pattern images. In this work we adopt such idea for denoising wrapped phase-maps. We use a regularized cost-function that uses complex-valued Markov random fields (CMRFs) with orientation information of the filtering direction along isophase lines. The advantage of using an anisotropic filter along isophase lines is that phase and noise can be properly separated while 2 pi phase jumps are preserved even in high frequency zones. Apart from its robustness, the outstanding advantage of our method is its minimal computational effort. We present some results processing simulated and real phase-maps.
  • Publication
    High dynamic range imaging method for interferometry
    (Elsevier Science B. V., 2011-08-15) 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.
  • Publication
    Direct demodulation of closed-fringe interferograms based on active contours
    (2010-11-01) 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.
  • Publication
    Optical method for the surface topographic characterization of Fresnel lenses
    (SPIE--The International Society for Optical Engineering, 2011) Martínez Antón, Juan Carlos; Gómez Pedrero, José Antonio; Alonso Fernández, José; Quiroga Mellado, Juan Antonio
    Fresnel lenses and other faceted or micro-optic devices are increasingly used in multiple applications like solar light concentrators and illumination devices. As applications are more exigent this characterization is of increasing importance. We present a technique to characterize the surface topography of optical surfaces. It is especially well adapted to Fresnel lenses where abrupt surface slopes are usually difficult to handle in conventional techniques. The method is based on a new photometric strategy able to codify the height information in terms of optical absorption in a liquid. A detailed topographic map is simple to acquire by capturing images of the surface. Some experimental results are presented. A single pixel height resolution of similar to 0.1 mu m is achieved for a height range of similar to 50 mu m. A surface slope analysis is also made achieving a resolution of similar to +/- 0.15 degrees.
  • Publication
    Robust fitting of Zernike polynomials to noisy point clouds defined over connected domains of arbitrary shape
    (The Optical Society Of America, 2016-03-21) Rodríguez Ibáñez, Diego; Gómez Pedrero, José Antonio; Alonso Fernández, José; Quiroga Mellado, Juan Antonio
    A new method for fitting a series of Zernike polynomials to point clouds defined over connected domains of arbitrary shape defined within the unit circle is presented in this work. The method is based on the application of machine learning fitting techniques by constructing an extended training set in order to ensure the smooth variation of local curvature over the whole domain. Therefore this technique is best suited for fitting points corresponding to ophthalmic lenses surfaces, particularly progressive power ones, in non-regular domains. We have tested our method by fitting numerical and real surfaces reaching an accuracy of 1 micron in elevation and 0.1 D in local curvature in agreement with the customary tolerances in the ophthalmic manufacturing industry.
  • Publication
    Squareness error calibration of a CMM for quality control of ophthalmic lenses
    (Springer London Ltd., 2013-09) Quiroga Mellado, Juan Antonio; Rodríguez Ibáñez, Diego; Alonso Fernández, José
    This paper proposes a calibration procedure for the squareness error of small-sized coordinate measuring machines like those used for ophthalmic lenses quality control. The proposed procedure only requires a spherical lens as a reference surface and it only needs to be measured once making this calibration method faster and cheaper than the existing ones.
  • Publication
    Role of the filter phase in phase sampling interferometry
    (The Optical Society Of America, 2011-10-10) Quiroga Mellado, Juan Antonio; Servín Guirado, Manuel; Estrada, Julio César; Vargas Balbuena, Javier; Torre Belizón, Francisco Javier de la
    Any linear phase sampling algorithm can be described as a linear filter characterized by its frequency response. In traditional phase sampling interferometry the phase of the frequency response has been ignored because the impulse responses can be made real selecting the correct sample offset. However least squares methods and recursive filters can have a complex frequency response. In this paper, we derive the quadrature equations for a general phase sampling algorithm and describe the role of the filter phase.
  • Publication
    Design of phase-shifting algorithms by fine-tuning spectral shaping
    (The Optical Society Of America, 2011-05-23) Quiroga Mellado, Juan Antonio; Servín Guirado, Manuel; Estrada, Julio César; González, Christhian Adonai
    To estimate the modulating wavefront of an interferogram in Phase Shifting Interferometry (PSI) one frequently uses a Phase Shifting Algorithm (PSA). All PSAs take as input N phase-shifted interferometric measures, and give an estimation of their modulating phase. The first and best known PSA designed explicitly to reduce a systematic error source (detuning) was the 5-steps, Schwider-Hariharan (SH-PSA) PSA. Since then, dozens of PSAs have been published, designed to reduce specific data error sources on the demodulated phase. In Electrical Engineering the Frequency Transfer Function (FTF) of their linear filters is their standard design tool. Recently the FTF is also being used to design PSAs. In this paper we propose a technique for designing PSAs by fine-tuning the few spectral zeroes of a PSA to approximate a template FTF spectrum. The PSA's spectral zeroes are moved (tuned) while gauging the plot changes on the resulting FTF's magnitude.
  • Publication
    Phase-shifting interferometry based on principal component analysis
    (The Optical Society Of America, 2011-04-15) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Belenguer Dávila, Tomás
    An asynchronous phase-shifting method based on principal component analysis (PCA) is presented. No restrictions about the background, modulation, and phase shifts are necessary. The presented method is very fast and needs very low computational requirements, so it can be used with very large images and/or very large image sets. The method is based on obtaining two quadrature signals by the PCA algorithm. We have applied the proposed method to simulated and experimental interferograms, obtaining satisfactory results.