Generation of cross-spectrally pure light by two diffusers moving in opposite directions and determination of diffuser surface roughness

In this study, it is shown that the light emerging from two pinholes, after it has passed through two identical diffusers having same correlation properties but moving in opposite directions with same linear speed, has the properties of cross-spectrally pure light. It is also shown that the visibility of the interference fringes formed in the observation plane is directly related to the characteristics of the diffuser, i.e. the average roughness of the diffuser surface. Therefore, by measuring the visibility of the interference fringes over a few pinhole separations, the average roughness of the diffuser surface can easily be determined. (C) 2002 Elsevier Science B.V. All rights reserved.