Sánchez Brea, Luis Miguel

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First Name
Luis Miguel
Last Name
Sánchez Brea
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
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Now showing 1 - 5 of 5
  • Publication
    Self-imaging technique for beam collimation
    (Optical Society of America, 2014) Sánchez Brea, Luis Miguel; Torcal Milla, Francisco José; Herrera Fernández, José María; Morlanes, Tomás; Bernabeu Martínez, Eusebio
    A simple collimation technique based on measuring the period of one self-image produced by a diffraction grating is proposed. Transversal displacement of the grating is not required, and then automatic single-frame processing can be performed. The self-image is acquired with a CMOS camera, and the period is computed using the variogram function. Analytical and experimental results are obtained, which show the simplicity and accuracy of the proposed technique.
  • Publication
    Near-field shaping with two binary diffractive optical elements in tandem
    (Elsevier Science BV, 2013-06-15) Herrera Fernández, José María; Sánchez Brea, Luis Miguel; Bernabeu Martínez, Eusebio
    Diffractive optical elements (DOEs) are commonly used for beam shaping in the far field. In the present work, we develop an algorithm for near-field beam shaping using a double DOE system with binary modulation, so that it can be easily implemented on a glass substrate. In a first stage, the first amplitude DOE is equal to the target intensity distribution and the second phase DOE is obtained using a simple and fast iterative technique. In order to improve the optical efficiency of the system, we also analyze the behavior of the algorithm when the first DOE is not equal to the target image, but a widened version of it. Several numerical simulations are obtained, and an analysis of tolerances is performed.
  • Publication
    Estrategias de iniciación a la experimentación en laboratorios de las enseñanzas en Óptica
    (2015) Martínez Matos, Oscar; Alieva Krasheninnikova, Tatiana; Canabal Boutureira, Héctor; Navarrete Fernández, María de la Cruz; Gonzalo Fonrodona, Isabel; Herrera Fernández, José María; Irigoyen Irigoyen, Maite; Luis Aina, Alfredo; Piquero Sanz, Gemma; Rodrigo Martín Romo, José Augusto; Sánchez Brea, Luis Miguel; Sánchez Martín, José Antonio; Serna Galán, Julio; Tercero Gómez, José Luis; Torcal Milla, Francisco José; Vilas Prieto, José Luis; Weigand Talavera, Rosa
    Se propone un cambio en la metodología docente de la asignatura Laboratorio de Física III del Grado en Física, para hacerla más dinámica y potenciar la participación e iniciativas de los estudiantes, adecuándola al espíritu de Bolonia
  • Publication
    Dual self-image technique for beam collimation
    (IOP Publishing, 2016-06-14) Herrera Fernández, José María; Sánchez Brea, Luis Miguel; Torcal Milla, Francisco José; Morlanes Calvo, Tomás; Bernabeu Martínez, Eusebio
    We propose an accurate technique for obtaining highly collimated beams, which also allows testing the collimation degree of a beam. It is based on comparing the period of two different self-images produced by a single diffraction grating. In this way, variations in the period of the diffraction grating do not affect to the measuring procedure. Self-images are acquired by two CMOS cameras and their periods are determined by fitting the variogram function of the self-images to a cosine function with polynomial envelopes. This way, loss of accuracy caused by imperfections of the measured self-images is avoided. As usual, collimation is obtained by displacing the collimation element with respect to the source along the optical axis. When the period of both self-images coincides, collimation is achieved. With this method neither a strict control of the period of the diffraction grating nor a transverse displacement, required in other techniques, are necessary. As an example, a LED considering paraxial approximation and point source illumination is collimated resulting a resolution in the divergence of the beam of σ φ = ± μrad.
  • Publication
    Lissajous figure-based single-frame collimation technique
    (Elsevier, 2015-09-01) Torcal Milla, Francisco José; Sánchez Brea, Luis Miguel; Herrera Fernández, José María
    An accurate collimation technique based on a double grating system is proposed. Transversal displacement of the grating is not required and then, automatic single-frame processing can be performed. Talbot self-images are projected onto a mask composed by several shifted diffraction gratings. A Lissajous figure is obtained with the signals acquired by a CMOS camera where the mask is simulated by software. The collimation degree is determined by measuring the ellipticity of the Lissajous figure. Visual or automatic procedures for simple and accurate collimation of a light source are proposed. Experimental results are obtained which show a resolution of δϕ ≈ 4.16 μrad in the divergence of the beam when a lens with focal length f = 25 mm and diameter D = 20 mm is used for collimation.