This paper describes a single-pulsed subtraction TV holography system for measuring high speed transient in-plane displacements generated over the surface of a test object under impact loading. Two separated single-pulsed speckle interferograms produced by a ruby laser which freezes the object motion are recorded using a TV camera and stored in a frame grabber. The computer used for image processing is used to control image acquisition. The electronic and software control devised to synchronize the laser pulses to the TV camera and the object position is also described. Transient displacements are determined by digital analysis of the fringes generated by the subtraction of the recorded speckle interferograms. As an example, in-plane displacements generated by the impact of a pendulum on a steel cantilever beam is presented.
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|Published - 1998