Person: González Cano, Agustín
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First Name
Agustín
Last Name
González Cano
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Óptica y Optometría
Department
Óptica
Area
Optica
Identifiers
44 results
Search Results
Now showing 1 - 10 of 44
Item Uniform-waist tapered optical fibers with double-layer deposition.(Second European Workshop On Optical Fibre Sensors: Proceedings, 2004) González Cano, Agustín; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; Esteban Martínez, Óscar; Bueno Guillén, Francisco JavierNovel devices consisting of uniform-waist tapered optical fibers with a double layer (metal plus dielectric) deposition are presented and their properties in terms of optical transmission are studied. Excitation of surface plasmons in the metallic layers is experimentally shown. These devices can be used as basis for new sensors.Item Measurement of the degree of salinity of water with a fiber-optic sensor(Applied Optics, 1999) Esteban Martínez, Óscar; Navarrete Fernández, María Cruz; González Cano, Agustín; Bernabeu Martínez, EusebioA fiber-optic sensor based on surface-plasmon resonance for the determination of the refractive index is used for measuring the degree of salinity of water. The transducing element consists of a multilayer structure deposited on a side-polished monomode optical fiber. Measuring the attenuation of the power transmitted by the fiber shows that a linear relation with the refractive index of the outer medium of the structure is obtained. The system is characterized by use of a varying refractive index obtained with a mixture of water and ethylene glycol. Experimental results show that the sensor can be used as a salinity-degree measurement device with environmental applications.Item Sensing properties of asymmetric double-layer-covered tapered fibers(Applied Optics, 2004) Bueno Guillén, Francisco Javier; Esteban Martínez, Óscar; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; González Cano, AgustínA novel, to our knowledge, device based on a tapered optical fiber with a double-layer deposition including a metallic media is presented, and its properties are studied. The main novelty of the device consists of the introduction of a dielectric layer, whereas the systems depicted in the literature are simply metal-coated tapered fibers. The presence of the dielectric layer permits one to tune the response of the device to the refractive index of the surrounding medium. We have proved the suitability of this scheme for refractive-index sensing by depicting two measurement modes, namely, total power attenuation and spectral transmittance.Item Automatic determination of isostatics in two-dimensional photoelasticity(Measurement Science and Technology, 2000) Quiroga Mellado, Juan Antonio; González Cano, AgustínWe present a method for automatic determination of isostatics from the photoelastic measurement of isoclinics obtained by phase-shifting techniques. The method is based on the integration of two difference equations by use of a multigrid algorithm, using a quality map obtained from experimental data by checking the consistency of the generated experimental differences. So-called isostatic sulfaces are determined and, from them, the isostatics net can be drawn with any prescribed density and resolution. The algorithm is very robust and fast and has proven very efficient for working with real photoelastic fringe patterns.Item Application of regularization methods to the analysis of photoelastic fringe patterns(Interferometry 99: Techniques and Technologies, 1999) Quiroga Mellado, Juan Antonio; González Cano, AgustínIn this work we present the application of a regularization algorithm to the processing of photoelastic hinge patterns. The method used is a modified phase tracking algorithm applied to phase-shifted images. In particular, we present an algorithm for isoclinics-isochromatics separation that uses only five images. The performance of the method is discussed and experimental results are presented.Item Stable-marriages algorithm for preprocessing phase maps with discontinuity sources(Applied Optics, 1995) Quiroga Mellado, Juan Antonio; González Cano, Agustín; Bernabeu Martínez, EusebioA new algorithm is proposed for solving the problems associated with discontinuity sources in phase maps. It is based on the stable-marriages algorithm and is implemented as a recursive procedure. With this technique, discontinuity sources of opposite sign are connected by a set of cut lines that fulfills a stability criterion and possesses the minimum cut length of the stable sets. The algorithm is fast and easy to implement and has proved efficient, as experimental results show.Item Extension of Surface Plasmon Resonance in fiber optic sensors into the visible region(Fifth European Workshop On Optical Fibre Sensors, 2013) Navarrete Fernández, María Cruz; Díaz Herrera, Natalia; González Cano, Agustín; Esteban Martínez, ÓscarIn this work we experimentally show how the technology of surface plasmon resonance (SPR) in doubly deposited uniform-waist tapered optical fiber sensors (DLUWTs) can be extended into the visible region (around 520 nm) by changing the thicknesses of the deposited layers. In this way, by using DLUWTs we can cover, in an easy and versatile way, a total wavelength range over 1000 nm wide, having shown in the past how this same kind of sensors can be usable in the communication band. The possibilities of fiber sensors can then be applied to the region of visible wavelengths, which is very interesting from the biological point of view.Item Improved performance of SPR sensors by a chemical etching of tapered optical fibers(Optics and Lassers in Engineering, 2011) Díaz Herrera, Natalia; Esteban Martínez, Óscar; Navarrete Fernández, María Cruz; González Cano, Agustín; Benito Peña, María Elena; Orellana Moraleda, GuillermoWe present the results of a chemical attack on the optical fiber surface previous to the deposition of the double layer (metal plus dielectric) in Double-layer uniform-waist tapered fibers (DLUWTs) used for the development of SPR sensors. It is shown how this simple chemical treatment increases the roughness of the surface and permits improvement of the stability of the deposits and the general performance of the sensors. The obtained devices are robust and very compact, their sensitivity is good and repeatability of the measurements is remarkably increased. The procedure can be useful for any fiber-optic sensor.Item DL-UWTs: novel devices for chemical and biological sensing(Third European Workshop on Optical Fibre Sensors, 2007) González Cano, Agustín; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; Esteban Martínez, ÓscarAlthough many optical fiber sensors have been proposed for chemical, environmental or biological measurements, it seems that the potential of this kind of devices has not been fully exploited. In this paper we discuss the possibilities of doubly-deposited uniform-waist tapered fibers (DL-UWTs) for the development of new sensors that can become a new standard in the field of Surface Plasmon Resonance (SPR) based sensors and contribute to the extension of the range of application of fiber technology to the mentioned fields. We also compare different configuration and evaluate some relevant features of DL-UWTs, as the possibility of fully independence of polarization or the excitation of multiple plasmons.Item A fibre-optic temperature sensor based on the deposition of a thermochromic material on an adiabatic taper(Measurement Science and Technology, 2004) Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; Esteban Martínez, Óscar; González Cano, AgustínA fibre-optic sensor has been developed for the measurement of temperature, especially of liquids. The device is conceived as part of an all-optical CTD probe for the control of the physical parameters of a marine medium. The dependence on temperature of the optical properties (specifically, absorbance) of a thermochromic material, namely lophine (2,4,5-triphenylimidazole), is the basis of the sensor. The sensor presents some significant differences with respect to other similar sensors proposed in the literature: the use of adiabatic, long, tapered optical fibres with adjustable geometric parameters; the use of LED illumination in the 800 nm range; improvements in the deposition technique, etc. The sensors show a linear behaviour over the desired temperature range, and their sensitivity is high. Also, the dependence of the response of the sensor with variations of the geometry of the tapers is discussed. Specifically, we have performed measurements with different diameters of the taper waist, and we show the dependence of the slope of the response curve with that parameter.