Surface roughness effects in dual beam illumination speckle interferometers: Theoretical study

Analyzed in this paper is the influence of surface roughness of the object on the quality of data or fringes obtained in dual beam illumination speckl e interferometers. The theoretical analysis is based on the electromagnetic scattering of light from rough surfaces by observing the modulation of the speckles in the dual beam illumination speckle interferometric setup. It i s shown that when object surface roughness is greater than the wavelength o f light the quality of the signal is dependent on the angle of illumination of the beam and also on the observation direction. Both in-plane and out-o f-plane sensitive dual beam illumination interferometers are investigated i n this paper. We show that in one specific arrangement the modulation of th e speckles is dependent on the surface roughness of the object being invest igated.