FRD - Investigación - Ciencia y Tecnología

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    Scanning optical coherence tomography applied to the characterization of surfaces and coatings
    (El Sevier, 2014) Cerrotta, Santiago; Morel, Eneas Nicolás; Torga, Jorge Román
    This paper shows the technique of optical coherence tomography in the frequency domain (OCT-FD) to obtain surface topography and tomography of surface coatings. The setup is based on a superluminescent diode centered on 849 nm with an spectral wide of 50 nm as the light source, a single-mode fibre Michelson interferometer and a spectrometer as the detector system. This scheme allows having compact and robust equipments that was designed to be used in an industrial environment. With this system it can be obtain a tridimensional image acquired point by point with a maximum range of 20 mm width and length and 2 mm depth. Images obtained from the topography of metal samples and tomography of polymer based coatings is presented. Also it is shown that is possible to obtain, from these images, parameters of interest of the sample, such as roughness, flatness and characteristic distances. As an example to show the potential of the method the dimensions of a metal surface modified after laser ablation were measured from a topography image obtained with this technique. A second example presented was the image obtained of a roughness pattern made on a metal surface. Finally it was presented a tomography image of a modified polyurethane coating deposited on a metal surface. Thickness and refractive index of the coating were obtained after the image analysis.
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    Dual system increases the resolution of a low coherence interferometer system through a signal detector astigmatic focus
    (2015-10-29) Morel, Eneas Nicolás; Aguilar, Andres; Torga, Jorge Román
    The low coherence interferometry in Fourier space (FD-OCT) is a technique to measure distance with typical values of dynamic range in the order of 3 mm and resolution below 10 microns. In this paper we propose to combine the interferometric technique with a technique that measures distances using astigmatic focus signal, allowing lead the resolution limit of less than 10 nm. The experimental scheme shown armed with both techniques and experimental results in displacement of a sample surface, controlled feedback system with a piezoelectric strain gauge which we have used as a reference system..
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    Dual system increases the resolution of a low coherence interferometer system through a signal detector astigmatic focus
    (2015-10-29) Morel, Eneas Nicolás; Aguilar, Andres; Torga, Jorge Román
    La interferometría de baja coherencia en el espacio de Fourier (OCT-FD) es una técnica que permite medir distancia con valores típicos de rango dinámico en el orden de 3 mm y resolución por debajo de los 10 µm. En este trabajo se propone combinar esta técnica interferométrica con una técnica que mide distancias utilizando la señal de foco astigmática, lo que permite llevar el límite de resolución a menos de 10 nm. Se muestra el esquema experimental armado con ambas técnicas y resultados experimentales en desplazamientos de una superficie muestra, controlada con un sistema piezoeléctrico realimentado con strain-gauge que hemos utilizado como sistema de referencia