Interferometric scanning microscopy for the study of disordered materials

We demonstrate an interferometric optical technique that probes pair-pair correlations in disordered materials. Fraunhofer diffraction patterns, using coherent double-probe illumination, exhibit Young's interference fringes whose strength is influenced by structural correlations between the two probed regions. Fourier transforms of diffraction patterns exhibit holographic sidebands, and the strength of correlations is proportional to the sideband intensity. Autoregression analysis of the correlation strength provides a direct measure of the characteristic ordering length scales. This technique is extendable in principle to x-ray and electron probes for studying materials at atomic length scales.