Speckles which is produced in the diffraction field as the results of Gaussian or non-Gaussian scattering of the coherent light (argon ion laser beam) by the deep random phase screen (ground glass) is investigated both theoretically and experimentally. The purpose of this research is to provide physical basis of the metrological application such as the measurement of the three dimensional velocity, surface roughness and the phase correlation length of the rough surface.
Theory on the Gaussian scattering deals with the determination of the three dimensional velocity from the second order temporal correlation of the speckles. And non-Gaussian scattering theory deals with the determination of the roughness and phase correlation length from the polar angle dependence of the mean intensity and fluctuation of the speckles.
Based on the theory, experiment is carried out with the rotating ground glass, where the rotating motion of the edge in the illuminated area is approximated to be linear motion. In the experiment on the Gaussian scattering, the two dimensional velocity vector normal to the optical axis is measured. And in the non-Gaussian scattering experiment, the surface roughness and phase correlation lengths of the ground glass with differing mesh#s(120 220, 320, 600, 1200) are measured. The surface roughness and phase correlation lengths are found to be decreasing from 8.88radian to 5.77radian and from 6.68um to 4.54um respectively with increasing mesh#.
