Electronic speckle pattern shearing interferometry for displacement and vibration measurement

E. A. Abd El-Ghafar; Hatem El-Ghandoor

doi:10.1117/12.363790

28 September 1999 Electronic speckle pattern shearing interferometry for displacement and vibration measurement

E. A. Abd El-Ghafar, Hatem El-Ghandoor

Proceedings Volume 3786, Optomechanical Engineering and Vibration Control; (1999) https://doi.org/10.1117/12.363790
Event: SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, 1999, Denver, CO, United States

Abstract

In this technique the speckle shear interferometer is combined with the electronic speckle pattern interferometry technique. Two pinholes of the same diameter 'a', separated by a distance 'd' is used to image through object through an imaging lens. The formed speckle pattern which is the resultant of mutual interference between the two speckle patterns formed by each pinhole, is modulated by a grid structure inside it. This pattern is imaged by a CCD camera combined with a reference beam through a beam splitter. The object under investigation is now photographed in its first state, without any deformation, and this signal is allowed to be stored in the computer as a data file. During the object vibration or deformation, a second signal is to be sorted on the same data filet. A fast Fourier transform has been used to add such tow signals and after processing the two overlapped signals data one can obtain the deformation suffered by the object in the form of interference fringes displaying such deformation.

Citation Download Citation

E. A. Abd El-Ghafar and Hatem El-Ghandoor "Electronic speckle pattern shearing interferometry for displacement and vibration measurement", Proc. SPIE 3786, Optomechanical Engineering and Vibration Control, (28 September 1999); https://doi.org/10.1117/12.363790

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