Fringe compensation displacement measurement using synthesized reference beam TV holography

The synthesized reference beam TV holographic technique is presented in this paper. In this method synthesized reference beams are used for compensating the deformation of the investigated object. The phase fronts of the reference beams are built from phase-shifted plane waves. These phase-shifted plane waves can be used periodically, so almost any phase front can be produced. The actual phase front can be built after the measurement using recorded pictures in the computer memory. Using this technique the sensitivity of the measurement can be changed after the recording, so this feature of the method is extremely valuable in industrial measurements, where repetition of the measurement is not always an easy task, In this way the fringe density at highly deformed points can be decreased, different components of the complicated fringe pattern can be removed, and the evaluation of the fringe system can be done more easily. This method can help to determine the sign of the deformation. A set of simulations and the results of real measurements are presented, (C) 1999 Elsevier Science B.V, All rights reserved.