Speckle correlation of changing surfaces

Abstract

ABSTRACT The study of light scattered from changing surfaces is of great interest because of its application in ageing control ofmechanical components and other problems. In a many situations it is important to know the roughness changes in dielectric or metallic surfaces. Often, this roughness variation must be determined in a non-destructive way. In this work it is reported some new results relatedwith the study of roughness variations. In recent works were presented some aspects of a developed theoretical modelthat relates the speckle correlation with changes in the surface roughness. This model is valid for dielectric or metallicsurfaces, however, for the sake of simplicity, it is studied a translucent diffuser.It is recorded the transmitted speckle pattern for a translucent rough surface before and after it suffers a change, and then it is calculate the correlation between both speckle patterns. The roughness is changed in a controlled way by means of immersion liquids of different refractive indices.A good agreement between the theoretical description and experimental results obtained in quasi-real time is achieved.