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Etude et réalisation d'un vibromètre holographique

Sébastien de Rossi 1
1 Laboratoire Charles Fabry de l'Institut d'Optique / Manolia
LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique
Abstract : We present and we characterize theoretically and experimentally a new holographic vibrometer, using the photorefractive dynamic of a semiconductor crystal as GaAs. It measures the instantaneous velocity of a vibrating target even with a rough surface. It is adapted to the measurement of high amplitude (as high some mm) low frequency (until some 10 kHz) vibrations. The tested point on the object is illuminated by a laser source. The signal wave reflected and scattered by the object is sent on the dynamic holographic material together with a coherent reference beam. These beams write in the material, an hologram of the wavefront structure of the signal beam. This hologram is read by the reference beam what creates in the direction of the transmitted signal beam a local oscillator that has exactly the same wavefront structure than the signal beam, whatever this structure. These two beams will then interfere in a wide field of view homodyne detection scheme, what will transform the phase modulation imprinted on the signal beam (and caused by the vibration of the object) into an intensity modulation. We have experimentally implemented the photorefractive velocimeter, in order to perform a first characterization of its performances. The performances of this vibrometer in the linear regime are essentially controlled by the response time of the photorefractive crystal. To increase the range of the performances we have showed the ability to extract the velocity of the target only using a optical treatment.
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Sébastien de Rossi. Etude et réalisation d'un vibromètre holographique. Physique [physics]. Université Pierre et Marie Curie - Paris VI, 2001. Français. ⟨tel-00009156⟩

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