FRLP - CIENCIAS BÁSICAS

Permanent URI for this collectionhttp://48.217.138.120/handle/20.500.12272/9849

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    Experimental fiber optic humidity sensor with applicability to civil structures health monitoring
    (2023) Alustiza, Diego; Mineo, Marcos; Arce, Valeria Beatriz; Villa Pérez, Cristian; Russo, Nélida Araceli
    This paper presents the results obtained in the execution of the first steps of the functional evaluation process of a fiber optic relative humidity sensor. The sensor device was a long period fiber grating (LPG) whose manufacturing process is described. Information is provided on how a humidity sensitivity level was reached that allows relative humidity (RH) measurements to be made. Packaging design implemented is described. Experimental arrangements used for thermal characterization and for humidity response are described. The results are discussed highlighting the details of the experimental setup to be improved in the future. Finally, the conclusions that qualify the feasibility of the implementation of an embedded humidity sensor in concrete structures by using this type of technology are provided.
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    Characterization of long period gratings manufactured with fiber optic fusion splicer for sensor development
    (2021) Alustiza, Diego; Mineo, Marcos; Russo, Nélida Araceli
    A Long Period Grating (LPG) is a structure inscribed in an optical fiber that is of great interest in the field of communications and sensors. At Centro de Investigaciones Ópticas (CIOp), an LPG manufacturing process was implemented. It is based on use of electric arcs produced with an optical fiber splicer to generate a series of physical disturbances that modify optical fiber behavior as a light transmis-sion guide. Since transmission response of LPG is sen-sitive to fiber environment conditions, it can be used to detect changes in certain physical and chemical pa-rameters. In particular, it enables the implementation of optical sensors sensitive to temperature, surround-ing medium refractive index and axial deformation. Characterization of locally generated LPGs is essen-tial for future design of sensors applicable in many engineering areas. In this article, typical LPG sensi-tivities to the three mentioned parameters are re-ported.
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    Light refraction in the earth’s atmosphere I. Inferior mirages: analytic solution of ray paths
    (2022-01-10) Paola, Carlos Alejandro; Cruzado, Alicia; Carrasco Galleguillos, Felix Marcial
    We aim to reach an analytic expression that describes the path of light rays through the Earth’s atmosphere in the particular situation in which an inferior mirage is occurring. To achieve our goal, we assume an exponential refractive index profile close to the ground, as suggested by empirical and theoretical studies on the state of air when an inferior mirage is taking place. We consider a parallel-plane atmosphere and assume that the laws of geometric optics apply. Since Fermat’s principle holds, we solve the Euler’s equation and, from the solution we obtain an analytic expression that describes the ray paths in a plane perpendicular to the ground. Given that we focus on the particular case of inferior mirages, we were able to find a very simple and easy-to-use expression to describe the ray paths, allowing us to extract additional valuable information with minimal computational effort. We take advantage of it to impose a limit to the thickness of the air layer next to the ground where appropriate conditions exist to bend the rays upwards, and produce an inferior mirage.
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    Light refraction in the earth’s atmosphere II. Inferior mirages: regions for images and objects observation
    (2023) Cruzado, Alicia; Cesanelli, Andrés; Paola, Carlos Alejandro
    In the present work, we analyze the different regions that are configured in a vertical plane for the visualization of the inferior mirage phenomenon. To achieve our goal, we take advantage of a methodology that we have previously developed to analytically obtain the path taken by any ray emerging from a point object, explicitly considering the atmosphere’s behavior near the surface. By means of this procedure we have reached analytical expressions, dependent on measurable temperature values, to delimit the observation regions in which it would be possible to see only objects, only images, both simultaneously, or none of them. From the expressions obtained, we study how these regions are distributed under different atmospheric conditions. The results obtained show that our methodology allow to predict the position (distance from the object and height from the ground) at which an observer should be located to observe the phenomenon, knowing the values of the air temperature at three different heights in the microlayer.
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    Radiation guided along a cylindrical symmetry system according to the refractive index profile
    (2020-08-25) Paola, Carlos Alejandro; Cruzado, Alicia
    We aim at finding, from purely theoretical analysis, the behavior that the refractive index should have within a cylindrical waveguide so that the radiation entering the system in a definite way is guided through it. Based on the criterion we have set in a previous article applying the Fermat’s extremal principle, in the framework of the geometrical optics, we depict the radiation confinement regions for refractive index profiles often used in the construction of waveguides, one step, multi-step and parabolic, by drawing upon the Legendre transform space as an intermediate resource in the process. We have also studied the possibility of performing the reverse path: for a wanted confinement region, to find the parameters defining the refractive index profile of the waveguide to be built. We conclude that such a process is possible as long as we know the shape of the profile. Under such restriction, our analysis allows us to deduce the characteristics that the guide should have so that the radiation entering with a given angle and at a certain distance from its axis remains confined. The technique can be used in design processes as a resource to limit the parameters that characterize the system.
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    Light refraction in the earth’s atmosphere III. Inferior mirages: images locus
    (2023) Paola, Carlos Alejandro; Cruzado, Alicia; Cesanelli, Andrés
    Our main goal is to find the locus of images formed as a result of an inferior mirage. To achieve our goal we show, at first, that, provided the beam entering a detection system has a small aperture, the image of a point object formed by that system in a vertical plane passing through the object is a point, regardless of whether the image formed by an optical system previously traversed by the beam has generated a non-point image of the object. Secondly, we show that the different images formed by the detection system, as its position relative to the object varies, are located on the caustic curve corresponding to the previously traversed optical system. Next, we have found the analytical expressions of the caustic curves corresponding to two particular cases, one of them being the inferior mirages. These expressions have been found by means of the Legendre antitransform of the asymptotic lines to the paths of light rays reaching the detector. For the case of inferior mirages, we have studied in detail the locus of the images in each vertical plane passing through the object as a function of the position of the object relative to the ground, its position relative to the detector, and the atmospheric conditions. Finally, we get somewhat into the matter of the images position as they would be seen by a casual observer of an inferior mirage.