Nondestructive Determination of Surface Flaw Geometry by Acoustical Holography, Exploratory Development.

Abstract : The results of experiments aimed at developing a new nondestructive method of investigating surface flaw geometry based on acoustical holography and a newly proposed liquid crystal read-out device are presented. The liquid crystal area detector was show to be feasible for use with acoustical holography; however, it was not applied to the monitoring of surface flaw geometry. The method was shown to have an order of magnitude improvement in resolution capabilities; however, it was found to be severely lacking in the area of sensitivity, re-sponse time, and dynamic range. A strict thermal activation of the liquid crystals by the ultrasound was found not to be the optimum. (Author-PL)