Digital Demodulation Using I/Q Signals and Optical Phase Control Applied to a Vibrometer
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Data
2020-10-01
Autores
Galvez-Limaco, Angel Manuel [UNESP]
Galeti, Jose Henrique
Nelli Silva, Emilio Carlos
Higuti, Ricardo Tokio [UNESP]
Connelly, Michael J.
Kitano, Claudio [UNESP]
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Editor
Ieee-inst Electrical Electronics Engineers Inc
Resumo
An efficient and cost effective optical phase detection vibrometer based on a modified closed loop homodyne Michelson interferometer is presented. Real-time phase demodulation is carried out, using an embedded platform that performs data acquisition, signal processing, PI (proportional-integral) control and the generation of signals that drive the electrooptic Pockels cell phase shifter and the piezoelectric actuator under test. Two phase quadrature signals are generated from a single interferometric output, using the interleaving action, in alternation, of a digitally generated modulating signal, and then the well-known differential-cross-multiplication technique is applied to perform the computation of the phase shift of interest. The quadrature condition is reached using the PI loop based on an error signal obtained from a Lissajous figure derived from out-of-phase signals. The vibrometer is capable of measuring nanometric displacements, and is simple, inexpensive, accurate, immune to fading and self-consistent. The new method was used to determine the displacement frequency response curves of two prototypes of multi-actuated flextensional piezoelectric actuators. Measurements were made between 500 Hz and 15 kHz, and the results agreed with those obtained by the standard SCM-Signal Coincidence Method.
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Palavras-chave
Optical interferometry, Optical sensors, Laser beams, Adaptive optics, Piezoelectric materials, Semiconductor device measurement, piezoelectric transducers, signal processing, metrology
Como citar
Ieee Sensors Journal. Piscataway: Ieee-inst Electrical Electronics Engineers Inc, v. 20, n. 19, p. 11313-11325, 2020.