ANGULAR-CORRELATION FUNCTION OF SPECKLE PATTERNS SCATTERED FROM A ONE-DIMENSIONAL ROUGH DIELECTRIC FILM ON A GLASS SUBSTRATE

We present the experimental results of the angular correlation functio n of far-field speckle patterns scattered by a one-dimensionally rando m rough surface of a thin dielectric film on a glass substrate when a polarized beam of light is incident upon the rough surface from vacuum . This surface, which separates the vacuum and the dielectric, is roug h enough that only diffused speckles are observed. The experiment for the correlation measurement was set up to make use of a CCD camera to obtain the image of the speckle pattern in the specular direction for each given angle of incidence; the cross-correlation function is then calculated from the digitized images. It is found that the intensity c orrelation functions exhibit two distinct maxima: one arises from the autocorrelation and the other from the reciprocity condition. It is al so found that different scattering processes give rise to quite differ ent correlation functions: multiple-scattering processes produce narro w peaks with secondary maxima and single-scattering processes produce relatively broad peaks. (C) 1997 Optical Society of America.