Some investigations in holographic microscopic interferometry with respectto the estimation of stress and strain in micro-opto-electromechanical systems (MOEMS)

Holographic microscopy with conjugate reconstruction for the interferometri c determination of three-dimensional displacement was used for the investig ation of the mechanical behaviour of micromechanic and microelectronic comp onents. An experimental set-up for the exposure of the holographic interfer ograms is described for the application of the spatial heterodyne technique , for the application of phase shifting, and for electro-optic holography, Three holograms for different illumination directions recorded on one holog raphic plate were reconstructed conjugately, and spatial-heterodyne techniq ue as well as phase-shift technique were used to evaluate the interferogram s. Only by conjugated reconstruction. it is possible to obtain a perfectly optimised interferometer for the static evaluation method. The evaluation o f interferograms, which are strongly disturbed by speckle noise. can be per formed successfully. A comparison of the results of the application of thes e techniques is given. The influence of the speckle effect on the resolutio n was investigated. (C) 2001 Elsevier Science Ltd. All rights reserved.