<title>Double-exposure holographic cinematography for in-situ vibration analysis</title>

Abstract

The use of a new interferometnc cineholography system allows new possibilities in the field of in-situ vibration analysis of structures: determination of phase and magnitude maps, calculation of the structural intensity and calculation of its divergence, modal analysis ofplates under complex excitation. This paper gives some results showing the feasability of such applications.

Wavenumber Processing Techniques to Determine Structural Intensity and Its Divergence from Optical Measurements without Leakage Effects

“…Equations (8)- (10) show that the normal component of the complex velocity in a plate suffices for calculations of the structural intensity, the divergence and the force distributions. The optical measurement techniques such as the holographic interferometry [10][11][12] and laser vibrometry [8,9] have well been applied to measure the vibrating complex velocity (amplitudes and phases) on the plate without contact. This section illustrates how to determine experimentally the complex vibrating velocity using the two optic techniques.…”

“…The cineholography technique was used for this study. Each double-exposure hologram is sampled at 25 Hz [12]. The method of speckle interferometry was also applied in some experimental measurements [19,23].…”

“…This approach was already associated with the techniques of near-field acoustic holography [2,7] and laser vibrometry measurements [8,9]. Holographic interferometry which makes it possible to obtain the data at high density of points, is necessary for processing in the wavenumber domain [10][11][12].…”