STUDY OF LASER SPECKLES IN THE PRESENCE OF SPHERICAL-ABERRATION

A study is made of the effect of lens aberrations when the size of the scattering spot is much smaller than the point-spread function of the optical system. In the presence of spherical aberration the speckle pattern takes a radially streaky appearance. The pattern has been studied at paraxial focus, marginal focus, plane of least confusion and a defocused plane. The appearance of the pattern is different at different planes. A heuristic explanation is given for such a streaky appearance. A simple experimental ray-tracing method provies a rough estimate of the average size of the speckles at different points in the observation plane.