DETECTION OF A SMALL DEFECT ON A ROUGH-SURFACE

We report experimental results that show that the far-field correlatio n function is sensitive to a small local change in rough-surface geome try, where the speckle spatial correlation rather than the sample ense mble average is adopted. The angular cross-correlation function of the far-field speckles scattered by one-dimensional random rough surfaces is measured when a polarized beam of light is incident upon the rough surface from vacuum, where one part of the surface used is a thin die lectric film deposited upon a glass substrate and the other part is id entical to the first except for a localized defect. We envisage applic ation of this sensitivity property to inspection of a sample with a de fect by means of speckle mapping. (C) 1998 Optical Society of America.