Análise teórica e experimental de um método interferométrico de detecção de fase óptica, auto-consistente e com elevada faixa dinâmica, aplicado à caracterização de atuadores piezoelétricos flextensionais
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Data
2009-05-25
Autores
Menezes, João Paulo Crivellaro de [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Atuadores piezoelétricos convertem energia elétrica em energia mecânica, sendo amplamente utilizados como transdutores de deslocamento micrométricos ou sub-micrométricos de elevada precisão. Neste trabalho, atuadores piezoelétricos flextensionais (APFs), projetados pelo método de otimização topológica, são caracterizados em termos de linearidade entre a tensão de excitação e o deslocamento gerado, bem como em termos de resposta em frequência, utilizando-se um interferômetro de Michelson homódino e em malha aberta. Interferômetros homódinos não realimentados têm seu desempenho prejudicado pelo fenômeno de desvanecimento, causado por perturbações ambientais espúrias que incidem aleatoriamente entre seus braços. Nesta dissertação, enfatizam-se métodos de demodulação de fase óptica baseados em relações envolvendo as componentes espectrais do sinal de saída do interferômetro que são imunes ao problema do desvanescimento. Dentre estes, destacam-se métodos clássicos como J1... J4, J1... J4 modificado, J1... J6 neg e J1... J6 pos. Estes métodos permitem a medição direta de deslocamentos microscópicos, sem a necessidade de qualquer procedimento de calibração. Além disso, não são afetados por instabilidades da fonte óptica, da responsividade do fotodiodo e da visibilidade das franjas de interferência. Contudo, apresentam reduzidas faixas dinâmicas de demodulação de fase. A fim de superar esta deficiência, investiga-se um método adicional de detecção direta, baseado na análise do espectro do sinal fotodetectado, exibindo todas as vantagens dos demais métodos, mas que é capaz de estender a faixa dinâmica de demodulação a valores tão elevados quanto 100 rad. Simulações computacionais são executadas com este método, levando-se em consideração o efeito do desvanecimento e tensões de ruído eletrônico do tipo 1/f, evidenciando...
Piezoelectric actuators convert electrical energy into mechanical energy, being widely used as micrometric or sub-micrometric displacement transducer of high accuracy. In this work, piezoelectric flextensional actuators (PFA’s), designed by the topology optimization method, are characterized in terms of linearity between the drive voltage and the corresponding displacement, as well as in terms of frequency response, using a homodyne, open-loop, Michelson interferometer. Homodyne interferometers without feedback have their performance spoiled by signal fading, caused by spurious environmental disturbances that occur randomly between their arms. This thesis emphasizes methods of optical phase demodulation, based on relations involving the spectral components of the interferometer output signal, which are immune to signal fading. Among these methods, it is detailed here the classical ones, such as J1... J4, modified J1... J4, J1... J6 neg e J1... J6 pos. These methods allow direct measurements of microscopic displacements, free of calibration procedures. Besides, they are not affected by optical source oscillations, photodiode responsivity and interferometric fringe visibility. However, they have reduced dynamic range for phase demodulation. In order to overcome this, this work investigates an additional method for direct detection, based on spectral analysis drawback of the photodetected signal. The method has all the advantages of the others, but it is able to span its demodulation dynamic range to values as high as 100 rad. Numerical simulations are done using this method (considering the signal fading and the 1/f electronic noise voltage), showing its viability to characterize PFA’s. Experiments are performed in laboratory, involving tests with different PFA’s. The method validation is carried out with the aid of an electrooptic intensity modulator, whose phase characteristics can... (Complete abstract click electronic access below)
Piezoelectric actuators convert electrical energy into mechanical energy, being widely used as micrometric or sub-micrometric displacement transducer of high accuracy. In this work, piezoelectric flextensional actuators (PFA’s), designed by the topology optimization method, are characterized in terms of linearity between the drive voltage and the corresponding displacement, as well as in terms of frequency response, using a homodyne, open-loop, Michelson interferometer. Homodyne interferometers without feedback have their performance spoiled by signal fading, caused by spurious environmental disturbances that occur randomly between their arms. This thesis emphasizes methods of optical phase demodulation, based on relations involving the spectral components of the interferometer output signal, which are immune to signal fading. Among these methods, it is detailed here the classical ones, such as J1... J4, modified J1... J4, J1... J6 neg e J1... J6 pos. These methods allow direct measurements of microscopic displacements, free of calibration procedures. Besides, they are not affected by optical source oscillations, photodiode responsivity and interferometric fringe visibility. However, they have reduced dynamic range for phase demodulation. In order to overcome this, this work investigates an additional method for direct detection, based on spectral analysis drawback of the photodetected signal. The method has all the advantages of the others, but it is able to span its demodulation dynamic range to values as high as 100 rad. Numerical simulations are done using this method (considering the signal fading and the 1/f electronic noise voltage), showing its viability to characterize PFA’s. Experiments are performed in laboratory, involving tests with different PFA’s. The method validation is carried out with the aid of an electrooptic intensity modulator, whose phase characteristics can... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Interferometria, Dispositivos piezoeletricos, Análise espectral, Optical interferometry, Piezoelectric flextensional actuators, Phase detection, Optoelectronic
Como citar
MENEZES, João Paulo Crivellaro de. Análise teórica e experimental de um método interferométrico de detecção de fase óptica, auto-consistente e com elevada faixa dinâmica, aplicado à caracterização de atuadores piezoelétricos flextensionais. 2009. 146 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Engenharia de Ilha Solteira, 2009.