%0 Journal Article
%T Submicron Surface Vibration Profiling Using Doppler Self-Mixing Techniques
%A Tania Pereira
%A Mariana Sequeira
%A Pedro Vaz
%A Ana Tom谷
%A Helena C. Pereira
%A Carlos Correia
%A Joˋo Cardoso
%J Advances in Optics
%D 2014
%R 10.1155/2014/576380
%X Doppler self-mixing laser probing techniques are often used for vibration measurement with very high accuracy. A novel optoelectronic probe solution is proposed, based on off-the-shelf components, with a direct reflection optical scheme for contactless characterization of the target＊s movement. This probe was tested with two test bench apparatus that enhance its precision performance, with a linear actuator at low frequency (35ˋ米m, 5每60ˋHz), and its dynamics, with disc shaped transducers for small amplitude and high frequency (0.6ˋ米m, 100每2500ˋHz). The results, obtained from well-established signal processing methods for self-mixing Doppler signals, allowed the evaluation of vibration velocity and amplitudes with an average error of less than 10%. The impedance spectrum of piezoelectric (PZ) disc target revealed a maximum of impedance (around 1ˋkHz) for minimal Doppler shift. A bidimensional scan over the PZ disc surface allowed the categorization of the vibration mode (0,ˋ1) and explained its deflection directions. The feasibility of a laser vibrometer based on self-mixing principles and supported by tailored electronics able to accurately measure submicron displacements was, thus, successfully demonstrated. 1. Introduction Laser Doppler velocimetry is a well-known measurement technique, widely used for accurate and remote measurement of fluid velocity and objects＊ displacement, velocity, and acceleration. The use of a laser diode (LD), both as an emitter and as a receiver of coherent light, allows for the capability to measure the velocity and displacement of a moving target surface. These optoelectronic elements, LDs, have been widely used in many different areas due to these remarkable features such as high sensitivity and accuracy, contactless operation, and a simplified optical scheme, when compared with most of the alternative sensors [1每4]. In order to measure the Doppler signal produced by a vibrating moving target, an optical probe based on a LD with self-mixing interference capabilities was used. This probe was tested with two different test benches in order to determine its ability to accurately measure velocity and other movement characteristics of a moving target. One test bench was composed by a linear actuator (35ˋ米m of amplitude) at low frequency (5每60ˋHz), other with disc shaped transducers with small amplitude (0.6ˋ米m) and high frequency (100每2500ˋHz). The optical solutions based on a LD with an algorithm for self-mixing signal processing represent an interesting tool to the determination of features of the movement described by PZ
%U http://www.hindawi.com/journals/ao/2014/576380/