Patent Document ID: 4139302
Application ID: 05769422
Patent Status: 1

Claim One:
1. The method of analyzing the strain on an object resulting from the application of a stress, comprising: illuminating the object with a coherent light source; exposing a photographic media to a first pair of focused images of the object displaced with respect to one another derived by passing light reflected from the object through a converging lens having a wedge-shaped prism covering a portion of its surface; stressing the object; exposing the photographic media to a second pair of focused images of the object, displaced with respect to one another as the first pair, after stressing, derived from said lens and prism; developing the photographic media; and analyzing the resultant image of the object with a fringe-frequency filter to create an image of the object with fringe families superimposed and arrayed as a function of the strain on the object.