REMOVING THE IMAGE-DOUBLING IN SHEAROGRAPHY BY RECONSTRUCTION OF THE DISPLACEMENT FIELD

摘要

In shearography a doubled speckle pattern is used to measure an approximation to the displacement derivative of a deformed object. In this paper a method is presented that reconstructs the original displacement field from a shearographic recording. The phase value representing the displacement of a point is calculated by adding the phase values of certain points in the shearogram. Applying this summation to all image points results in a fringe pattern that represents the displacement field with the effect of shear distance (i.e. the image-doubling) removed. Experiments performed with a simulated as well as with a measured shearogram show that the theoretically derived method works in practice. Since a shearography set-up with a single illuminating beam is used for recording and the result of the subsequent procedure is a displacement field, this method could be considered the realization of a single-beam electronic speckle pattern interferometer. [References: 15]