Measurement of deformation in a cylindrical shell by holographic interferometry.

In order to establish the quantitative method for measuring three-dimensional displacements by holographic interferometry, the authors have already discussed some problems and presented several practical devices. On the basis of these considerations, the usefulness of this measuring method was shown by a practical example: measurement of deformation in a cylindrical shell under concentrated loading. The displacement components could be measured with high accuracy (order of 0.1 microm) when the optical system was arranged and the fringe order number was read within allowable error given beforehand, respectively. The decision of fringe order number was made easily by applying elastic elongation of a rubber strip as an index and by reconstructing the holographic real image on the original object.