Publication: Vibrómetro de fibra óptica codificado en frecuencia
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2013-06
Defense date
2013-10-04
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Abstract
En el presente proyecto se expone el desarrollo de un vibrómetro basado en fibra óptica. La motivación de este proyecto es el diseño de un sistema capaz de monitorizar las vibraciones de una máquina mediante el uso de tecnología láser y de fibra óptica. Mediante este sistema es posible el cálculo de la frecuencia y amplitud de la vibración de la máquina. El vibrómetro está basado en el principio de interferencia de la luz. Un haz de luz coherente proporcionado por un láser se divide en dos: uno recorre una fibra óptica anclada a la máquina en uno de sus extremos y se compara con el otro que recorre otra fibra óptica de longitud fija tomada como referencia. La combinación de ambos provoca un patrón de interferencia que contiene información de la vibración. Para la medida se utiliza un interferómetro de fibra óptica. Bajo las condiciones seleccionadas para la amplitud y componentes de frecuencia de las vibraciones, la medida está contenida en la frecuencia de la señal de salida. Realizando una demodulación del patrón de interferencia obtenido a la salida del interferómetro es posible calcular los parámetros característicos de la vibración. Para realizar esa demodulación se ha diseñado un algoritmo implementado en un instrumento virtual mediante LabVIEW. El registro de las señales se ha llevado a cabo mediante el módulo de adquisición de alta velocidad CS328A, de CleverScope. Para integrar la adquisición de las señales con el análisis mediante los instrumentos virtuales se han programado los drivers proporcionados por los fabricantes.
Para realizar las medidas de calibración, se ha construido un dispositivo capaz de forzar una vibración controlada e integrar el sensor de fibra óptica. Este dispositivo está basado en un altavoz controlado mediante un generador de funciones. Junto con la fibra óptica, al altavoz se le ha acoplado un acelerómetro, que proporciona la referencia de medida de la vibración durante los ensayos de calibración del sistema completo.
In this project is exposed the development of a fiber optic based vibrometer. The motivation of this project is the design of a system able to monitor the vibration of a machine by the usage of laser and fiber optic technology. Through this system we are able to calculate the frequency and amplitude of the vibration of a machine. The vibrometer is based on the light interference principle. A beam of coherent light provided by a laser is divided in two beams: one of them travels across a fiber optic fixed to the machine and is compared with the other beam which travels through a constant length fiber that is used as a reference. The combination of both beams result in an interference pattern which contains the information of the vibration. A fiber optic interferometer is used to do the measurements. Under the selected conditions for amplitude and frequency components, the measurement is included in the frequency of the output signal. Performing a demodulation of the interference pattern obtained at the output of the interferometer we are able to estimate the characteristic parameters of the vibration. To do that demodulation an algorithm implemented on a virtual instrument programmed on LabVIEW has been designed. The signal had been acquired by the high speed module CS328A by CleverScope. To integrate the signal acquisition and the analysis by the virtual instruments the drivers provided by the manufactures had been programmed. To do the calibration tests a device capable to force a controlled vibration and integrate the fiber optic sensor has been built. This device is based on a speaker controlled by a function generator. In addition, an accelerometer has been fixed to the speaker to provide the measures’ reference of the vibration during the calibration test of the whole system.
In this project is exposed the development of a fiber optic based vibrometer. The motivation of this project is the design of a system able to monitor the vibration of a machine by the usage of laser and fiber optic technology. Through this system we are able to calculate the frequency and amplitude of the vibration of a machine. The vibrometer is based on the light interference principle. A beam of coherent light provided by a laser is divided in two beams: one of them travels across a fiber optic fixed to the machine and is compared with the other beam which travels through a constant length fiber that is used as a reference. The combination of both beams result in an interference pattern which contains the information of the vibration. A fiber optic interferometer is used to do the measurements. Under the selected conditions for amplitude and frequency components, the measurement is included in the frequency of the output signal. Performing a demodulation of the interference pattern obtained at the output of the interferometer we are able to estimate the characteristic parameters of the vibration. To do that demodulation an algorithm implemented on a virtual instrument programmed on LabVIEW has been designed. The signal had been acquired by the high speed module CS328A by CleverScope. To integrate the signal acquisition and the analysis by the virtual instruments the drivers provided by the manufactures had been programmed. To do the calibration tests a device capable to force a controlled vibration and integrate the fiber optic sensor has been built. This device is based on a speaker controlled by a function generator. In addition, an accelerometer has been fixed to the speaker to provide the measures’ reference of the vibration during the calibration test of the whole system.
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Keywords
Vibraciones, Vibrómetro, Fibras ópticas, Interferometría láser, LabVIEW, Optoelectrónica