The Laplace Transform of the time interval probability between successive photoelectrons in quasi-elastic light scattering experiments has proved to be an excellent method to overcome the problems derived of low scattered intensity conditions (i.e. low density of scatterers or the analysis of the depolarized component of the scattered light). The Laplace Transform method is discussed in some interesting cases. First, the description of the method is put forward in the case of a monodisperse solution of spherical or rod-like macromolecules. Afterwards, an analysis of binary mixtures is presented for the cases of a) two kinds of spherical particles (two sizes), and b) a mixture of spherical and rod-like particles. Finally, the more general case, i.e. poly-dispersity samples due to the presence of a size distribution, is addressed. Both theoretical and experimental results are presented, and they are compared with those obtained from conventional techniques of photon correlation spectroscopy.