Calvo Padilla, María Luisa

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First Name
María Luisa
Last Name
Calvo Padilla
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
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Search Results

Now showing 1 - 10 of 26
  • Publication
    Multiple scattering of classical electromagnetic waves by volume gratings: completion of Fujiwara's solution
    (Taylor and Francis Ltd., 1999-02-15) Calvo Padilla, María Luisa; Cheben, Pavel
    We present a general formulation for multiple scattering of classical electromagnetic waves by volume gratings. Fujiwara's electron multiple scattering theory is modified and extended to the case of both, the transmission and the reflection geometries. The analytical solution for the amplitude Φ_n corresponding to the nth scattering order is given. The convergence of the solution is proved for the transmission by a sinusoidal symmetric phase grating. By employing a structural Green's function and a vectorial formulation for diffraction of a classical electromagnetic wave by a thin periodical slab, as previously given by Alvarez-Estrada and Calvo, the solution for the back scattered field amplitude is derived and shown to coincide with that obtained within the framework of the multiple scattering theory.
  • Publication
    Edge image quality assessment: a new formulation for degraded edge imaging
    (Elsevier Science BV, 1998-12) Manzanares Ituarte, Ana; Calvo Padilla, María Luisa; Chevalier dl Río, Margarita; Lakshminarayanan, Vasudevan
    We discuss a formalism to characterize degraded edge images formed in a diffraction limited system (with circular pupil of unit radius) under conditions of incoherent illumination. We introduce a novel definition of degraded edges and consider this approach to model a basic optical mechanism involved in the perception of visual depth and edge detection. We introduce a degradation parameter to quantize the degree of edge blur. We present a generalization of such a procedure by assuming the Heaviside function to be a systematic generator of degraded edges. We reproduce experimentally the predictions made by the formalism proposed herein.
  • Publication
    Edge And Line Detection - Interpretation Using The Conrady Criterium
    (The International Society of Optical Engineering (SPIE), 1993) Calvo Padilla, María Luisa; Chevalier del Río, Margarita; Lakshminarayanan, Vasudevan
  • Publication
    Wave-front conversion between a Gaussian beam with a cylindrical phase function and a plane wave in a monomode on-axis transmission holographic coupler
    (Optical Society of America, 1993-12) Cheben, Pavel; Calvo Padilla, María Luisa
    We present a coupled-wave-analysis-based treatment for a wave-front conversion problem between a Gaussian beam with a cylindrical phase and a plane wave for a two-dimensional on-axis geometry. A coupled-wave approach to the multiple-scattering process in an inhomogeneous dielectric medium offers a clear physically interpretable description of the diffraction phenomena in volume media as well as the possibility of an intelligible mathematical treatment. An analytical integral solution for the amplitudes of the two modes of diffraction is submitted. High diffraction efficiency (≈1) and the deterioration of reconstruction fidelity are predicted. It is of interest to apply the model to the analysis and design of a monomode holographic fiber-to-fiber coupler, wave-front correctors, and holographic interconnection devices.
  • Publication
    Teorías de la difracción de ondas electromagnéticas por redes de volumen: Una revisión
    (Sociedad Mexicana de Física, 1998-08) Cheben, Pavel; Calvo Padilla, María Luisa
    Se presenta una revisión de las teorías de la difracción de ondas electromagnéticas por redes de volumen. En el enfoque de este trabajo se encuentran las teorías de los siguiente grupos: teorías de ondas acopladaseorías modales, teorías de dispersión múltiple y teorías electromagnéticas, siempre y cuando sean apropiadas para el análisis de redes de volumen. Se incluye también una revisión de teorías y métodos con menor impacto en el campo estudiado, tales como teorías de medio efectivo, método de difracción por el entorno, método de elementos finitos o algoritmos microgenéticos. Se recogen un tofal de 225 publicaciones seleccionadas que abarcan un período de aproximadamente cien años: 1891-1997.
  • Publication
    Resolution criterion and contrast factor for resolving two-line images under coherent and incoherent illumination
    (SPIE--The International Society for Optical Engineering, 1990) Mondal, Pronab K.; Chevalier del Río, Margarita; Calvo Padilla, María Luisa
    We define a resolution criterion for the case of two narrow line images. For doing so, we have considered the two lines as superposition of gradients of two Heaviside step-functions.
  • Publication
    Digitally generated soft edges with predetermined luminance: An analysis of its influence on image degradation.
    (SPIE--The International Society for Optical Engineering, 1998) Sanz, Inmaculada; Calvo Padilla, María Luisa; Chevalier del Río, Margarita
    The presence of degraded or soft edges on a scene or digital image may cause ambiguities in depth perception(1,2). This kind of edges has been analyzed by introducing a mathematical model to digitally implement a large category of degraded edges. This model has accounted the origin of degradation, the performance of psychophysical test for measuring the degradation perception, and image characteristics currently used in artificial vision as momenta, number of gray scale level per pixels, etc. It is the subject of current researches to be applied to artificial reproduction of human visual perception.
  • Publication
    Light propagation in optical waveguides: A dynamic programming approach
    (Optical Society of America, 1997-04) Lakshminarayanan, Vasudevan; Calvo Padilla, María Luisa
    We apply techniques of optimal-control theory, namely, the methods of dynamic programming, to the problem of light propagation in optical waveguides. This formulation is equivalent to the resolution of an eikonal equation. We illustrate this optimization technique for the case of an ideal parabolic refractive-index-profile distribution. We discuss the possibility of extending this procedure to other types of optical waveguides and optical media.
  • Publication
    Point spread function and modulation transfer function of a photolens treated as a cascade linear system under the Fresnel regime: application to a Tessar lens
    (Spie-Soc Photo-Optical Instrumentation Engineers, 1990-03) Calvo Padilla, María Luisa; Lakshminarayanan, Vasudevan
  • Publication
    High efficiency off-axis holographic coupler
    (Elsevier Science BV, 1992-03-01) Calvo Padilla, María Luisa; Cheben, Pavel
    This paper presents a high efficiency holographic coupler design for telecommunication purposes. It is based on the eikonal approach to diffracted field analysis and on the coupled wave analysis for gaussian beam in generalized coordinate.