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Laser Doppler Vibrometry system for measurement of vibration/velocity

Grant number: 12/02148-2
Support type:Scholarships abroad - Research Internship - Master's degree
Effective date (Start): May 21, 2012
Effective date (End): August 20, 2012
Field of knowledge:Engineering - Electrical Engineering - Electrical, Magnetic and Electronic Measurements, Instrumentation
Principal researcher:Ricardo Tokio Higuti
Grantee:Paula Lalucci Berton
Supervisor abroad: Michael J. Connelly
Home Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil
Research place: University of Limerick (UL), Ireland  
Associated to the scholarship:10/13868-0 - Analysis and implementation of microvibration measurement techniques using optical interferometry and digital signal processors, BP.MS

Abstract

It is proposed an internship at University of Limerick, Department of Electronic and Computer Engineering, Optical Communications Research Group, on vibration measurement using optical techniques. Laser Doppler Vibrometry (LDV) is based on interference of two laser beams, being a kind of optical interferometry. One of the beams is reflected by a vibrating object and is therefore Doppler shifted in frequency. This beam is mixed with a reference beam and the resulting one is detected by a photodetector. The resulting signal is a nonlinear function of the dynamic phase shift between the beams, but it is also dependent on the ambient conditions around the interferometer. The use of sophisticated signal processing techniques, e.g. synthetic-heterodyne, is required to linearise the system response and to reduce its dependence on ambient conditions. This project will involve the design and implementation of a conventional LDV system based on an acousto-optic modulator and the measurement of the vibration/velocity of two test objects: a vibrating mirror and a spinning CD. The performance of the conventional LDV system will be compared to that of a synthetic-heterodyne LDV system already in operation at the University of Limerick. In addition, the LDV systems will be used for vibration measurements of piezoelectric actuators in use at the Optoelectronics Laboratory of UNESP. These results will be compared to those obtained with the techniques used in the master's degree project. (AU)