OPTICAL DIFFRACTION OF STRETCHED LACUNARY SPRING NETWORKS

A network of randomly occupied sites connected by springs is submitted to an external stretch ; the optical diffraction pattern of the disto rted network is experimentally and analytically studied. Some regions are just shifted as a whole and related shifts are measured by means o f diffraction, some regions are uniformly distorted and this distortio n is optically detected. The techniques of pattern reconstruction in r eal space by filtering in Fourier space enable typical defects to be l ocalized. Fractal random media are also considered.