TRANSIENT INPLANE DEFORMATION ANALYSIS BY MEANS OF PULSED TV HOLOGRAPHY

This paper describes a single-pulsed subtraction TV holography system for measuring high speed transient in-plane displacements generated ov er the surface of a test object under impact loading. Two separated si ngle-pulsed speckle interferograms produced by a ruby laser which free zes the object motion are recorded using a TV camera and stored in a f rame grabber. The computer used for image processing-is used to contro l image acquisition. The electronic and software control devised to sy nchronize the laser pulses to the TV camera and the object position is also described. Transient displacements are determined by digital ana lysis of the fringes generated by the subtraction,of the recorded spec kle interferograms. As an example, inplane displacements generated by the impact of a pendulum on a steel cantilever beam is presented.