REAL-TIME DISPLACEMENT MEASUREMENT USING A MULTICAMERA PHASE-STEPPINGSPECKLE INTERFEROMETER

Surface point displacements can be measured by using standard phase-st epping speckle interferometry, but the measured data are vulnerable to disturbances during the interferogram recordings. To overcome this an interferometer with a computational system has been developed to reco rd three phase-stepped interferograms simultaneously and to calculate displacements. This system is evaluated by measurements of the out-of- plane rotation of a flat surface. The surface displacement is calculat ed at a rate of 25 times/s. If one reduces noise by filtering, hardwar e limitations decrease the speed to 12.5 displacement calculations/s. With this system displacements can be measured with an accuracy exceed ing lambda/55 if filtering is applied.