3D full field dynamical characterization of micromechanical devices by stroboscopic white light scanning interferometry

White light fringe scanning interferometric profilometry is increasingly used for 3D full field measurements of the surface topography and of the static deformations of MEMS because it can be applied, contrary to most interferometric technique using monochromatic illumination, to surfaces having large discontinuities and patterns with a complex geometry. In this paper it is demonstrated that this technique is also well suited for 3D full field measurements of MEMS vibrations provided that a stroboscopic LED array source is used. A fast algorithm based on quadrature filtering of the interferometric signal is described to determine for each pixel the maximum of the fringe envelope when the sample is translated. 3D measurements of the vibration modes of micromechanical devices with a complex shape and/or an initial deformation are demonstrated up to 570 kHz. A spatial resolution in the micrometer range and a detection limit of 5 nm have been obtained.