New analytical expression for speckle contrast of spectral light broadening

A new analytical expression for the average speckle contrast is derived for surfaces of random roughness at reflection. Rayleigh and Simpson phase probability density distributions of non-zero phase mean value are assumed for the roughness of the surface. The behavior of a speckle contrast with a roughness root mean square of phase deviation is presented. The effect of the spectral light profile, its spectral width, the density of the scatterers of the rough surface and the average time delay between the interfering beams are taken into consideration. (paper)