2D full field vibration analysis with multiplexed digital holograms

Abstract

Opportunities for full field 2D amplitude and phase vibration analysis are presented. It is demonstrated that it is possible to simultaneously encode-decode 2D the amplitude and phase of harmonic mechanical vibrations. The process allows the determination of in plane and out of plane vibration components when the object is under a pure sinusoidal excitation. The principle is based on spatial multiplexing in digital Fresnel holography. Experimental results are presented in the case of an industrial application.

Real-Time Colour Holographic Interferometry (from Holographic Plate to Digital Hologram)

“…At the same time, two wavelength profilometry was proposed in a digital holographic microscope using two laser diodes (680nm, 760nm) and a monochrome sensor, giving a synthetic wavelength of 6.428m (Kuhn et al, 2007). The method is based on a spatial multiplexing by incoherent addition of single-wavelength interferograms, in the same way as was developed by Picart et al, 2003Picart et al, , 2005, with a single wavelength, each having different propagation directions for the reference waves, and recording with a monochrome CCD. As regards these works, ONERA and LAUM 5 decided to join theirs respective competences acquired in the past in order to develop adaptable and new optical imaging methods, firstly having properties such as full field imaging with high spatial and temporal resolutions, secondly giving absolute data after post processing and finally giving dynamic three dimensional measurements.…”

Two-dimensional optical coherence tomography for real-time structural dynamical characterization

“…MacPherson et al [12] reported a multipoint laser vibrometer which is capable of resolving 256 measurement points. Speckle interferometry [13][14][15][16], holographic interferometry [6,17,18], heterodyne interferometer [19] and Self-mixing interference [20] enable reliable measurements of mechanical vibrations. However, for these interferometer techniques [1][2][3][4][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], the displacement is obtained from the phase change of the interferometric patterns, providing extremely high depth resolution (down to 10 À 12 m or 1 pm) [21].…”

Study of the Mechanical Behaviour of a Clarinet Reed Under Forced and Auto-oscillations With Digital Fresnel Holography

“…So, pseudo-pulsed digital holography was developed for reconstructing both amplitude and phase of the vibration [11]. An extension of this principle into simultaneous 2D full-field vibration analysis by combining digital holography and spatial multiplexing of holograms was also proposed [12]. However, such a strategy is only valid for monochromatic sinusoidal vibrations.…”